Meet your virtual financial coach. Learn how machine learning and AI are democratizing wealth management, offering robo-advisors, predictive analytics, and tailored investment strategies for every budget.
The world of retirement planning is witnessing a significant transformation as AI-driven financial tools challenge traditional human advisory services. With robo-advisors projected to manage $2.4 trillion by 2029, investors face a critical choice between algorithms offering low-cost portfolio management and human advisors providing personalized guidance for complex financial situations.
Key Takeaways
- Robo-advisors charge 0.25%-0.50% annually versus human advisors at 1%-2%, potentially saving thousands in fees
- AI advisors excel with simple portfolios under $50,000, while humans deliver more value for complex financial situations and portfolios over $500,000
- Hybrid models combining AI efficiency with human oversight represent the fastest-growing segment in financial advisory services
- 84% of clients report satisfaction with human advisors versus 77% for robo-advisors, highlighting the ongoing value of emotional intelligence in financial planning
- Tax-loss harvesting by platforms like Betterment covers advisory fees for nearly 70% of clients, offering tangible cost benefits
The Financial Advisory Landscape: AI vs Human Financial Advisors
The financial advisory space is experiencing remarkable disruption as automated investment platforms gain traction. Current market data shows robo-advisor assets under management (AUM) will grow from $754 billion in 2024 to a projected $2.4 trillion by 2029, representing a 15.47% compound annual growth rate. Despite this impressive growth, human advisors still manage approximately 85% of U.S. investment assets.
Market leaders in the robo-advisory space include Vanguard Digital Advisor with a dominant $311.9 billion AUM, followed by Empower ($200 billion) and Schwab Intelligent Portfolios ($80.9 billion). The rapid expansion of these platforms is directly challenging the traditional financial advisory model, creating both opportunities and concerns for retirement investors.
Cost Comparison: The Fee Advantage
One of the most compelling advantages of robo-advisors for retirement planning is their significantly lower fee structure. While traditional human advisors typically charge between 1% and 2% of assets annually, robo-advisors offer similar core services for just 0.25% to 0.50% annually. This difference might seem small, but it compounds dramatically over decades of retirement saving.
The cost difference extends beyond percentage-based fees. Human advisors often require substantial minimum investments (frequently $50,000 or more) and may charge additional fees such as:
- Hourly consultations ($200-$400)
- One-time financial plans ($1,000-$3,000)
- Annual retainer fees ($2,000-$7,500)
In contrast, many robo-advisors have eliminated minimum investment requirements entirely. Betterment has no minimum balance requirement, while Vanguard Digital Advisor requires just $100 to start investing. This accessibility makes automated advisors particularly attractive for younger investors or those with limited initial capital.
Tax-loss harvesting represents another significant cost advantage. Betterment reports that nearly 70% of their clients had advisory fees effectively covered by tax-loss harvesting benefits, creating a nearly cost-neutral advisory relationship for many users.
Portfolio Size Scenarios: Finding Your Fit
The optimal choice between AI and human advisors often depends on portfolio size and complexity. Let’s examine three common scenarios:
For a $10,000 starter portfolio, a robo-advisor clearly wins on cost efficiency. At 0.25%, the annual fee would be just $25, compared to human advisors who might not even accept such accounts due to minimum requirements. The automated diversification and rebalancing provided by platforms like Wealthfront or Betterment are perfectly suited for simple, growth-oriented portfolios.
With a $500,000 mid-career portfolio, the decision becomes more nuanced. A robo-advisor charging 0.25% would cost $1,250 annually, with tax-loss harvesting potentially adding 1% in returns. However, skilled human advisors might achieve higher risk-adjusted returns through tactical rebalancing and personalized strategies that justify their higher fees.
For a $2 million retirement portfolio, human advisors typically provide superior value despite higher costs. Advanced estate planning, tax-optimized withdrawal strategies, and legacy planning can save retirees $200,000 or more over time – far outweighing the fee differential. Complex situations involving multiple asset classes, family considerations, and tax planning benefit substantially from human expertise.
Core Retirement Planning Features Comparison
Both AI and human advisors offer essential retirement planning features, but with notable differences in approach and capabilities. AI financial planning tools excel at creating diversified ETF portfolios tailored to risk tolerance and time horizons. Vanguard’s Life-Cycle Investing Model and similar algorithms from Fidelity Go automatically adjust asset allocation as retirement approaches.
Among the leading robo-advisory platforms, Betterment manages $45.9 billion, Schwab Intelligent Portfolios oversees $80.9 billion, and Wealthfront handles approximately $75 billion in client assets. These platforms offer automated portfolio construction based on modern portfolio theory principles.
Human advisors provide distinct advantages in creating sustainable withdrawal strategies that consider tax implications and adapt to market volatility. They also excel at adjusting plans for major life changes such as inheritances, healthcare costs, or career transitions. The goal-based assessment tools used by robo-advisors often lack the nuance to address these complex life scenarios effectively.
When Complexity Demands Human Expertise
Certain financial situations benefit substantially from human guidance. These include:
- Multi-asset management: Human advisors can integrate real estate, private equity, and other alternative investments that most robo-platforms cannot accommodate
- Estate and tax planning: Creating trusts, legacy planning, and optimizing tax brackets becomes critical for portfolios over $2 million
- Behavioral coaching: Humans provide invaluable support during market downturns, helping clients avoid panic-driven decisions
I’ve observed that clients with complex financial situations often find robo-advisors too limiting. While machine learning algorithms optimize portfolios effectively for standard situations, they struggle with interconnected decisions involving multiple financial instruments, family dynamics, and irregular income patterns.
A comparison of portfolio complexity versus advisor suitability reveals that as financial situations become more intricate, the value of human guidance increases proportionally. This is especially true for high-net-worth individuals with diverse assets and complex tax situations.
The Human Element: Emotional Intelligence in Financial Planning
The psychological aspects of financial planning shouldn’t be underestimated. A Vanguard study found that 84% of clients working with human advisors reported satisfaction with their services, compared to 77% of robo-advisor users. This satisfaction gap reflects the value of emotional intelligence in financial relationships.
Human advisors provide crucial support during major life transitions such as divorce, job loss, or inheritance. These emotional moments require empathy and personalized guidance that algorithms simply cannot replicate. While AI tools like MoneyGuide Pro and RightCapital provide excellent data insights, they lack the relational depth that many clients value.
The human advantage extends to understanding non-financial factors and family dynamics that impact financial decisions. Advisors develop deep knowledge of clients’ values, priorities, and personal circumstances, allowing for truly customized financial strategies rather than algorithmic approximations.
Hybrid Models: The Best of Both Worlds
The future of financial advice increasingly points toward hybrid models that combine AI efficiency with human oversight. Vanguard Personal Advisor Services exemplifies this approach, blending algorithms with certified financial planners for accounts over $50,000. This combination aims to deliver cost-effective personalization at scale.
Technology continues to enhance advisor capabilities through AI augmentation tools. Zocks integrates with eMoney for automated data entry, while Qdeck uses GPT models to improve client communications. These tools boost advisor productivity without replacing the human element.
Advisors increasingly leverage specialized software like MoneyGuide Pro for real-time data aggregation and RightCapital for tax optimization. These technologies allow human advisors to focus on high-value activities while automation handles routine tasks. The resulting workflow optimization enables advisors to serve more clients effectively while reducing overall costs.
Making Your Decision: Key Factors to Consider
When deciding between AI and human financial advisors for retirement planning, several key factors should guide your choice:
- Portfolio size: Robo-advisors are typically ideal for portfolios under $50,000 with simple needs
- Complexity indicators: Choose human advisors for multi-asset portfolios, estate planning needs, or when emotional support is valuable
- Cost sensitivity: If minimizing fees is your primary concern, robo-advisors offer significant savings
- Time horizon: Younger investors with decades until retirement may benefit from low-cost robo solutions
The hybrid option provides balance for portfolios between $50,000 and $500,000, offering cost efficiency with human oversight. This middle path is gaining popularity as investors seek both technological efficiency and personalized guidance.
Future trends suggest growing hybrid adoption as technology enhances rather than replaces human advisory services. The AI vs human financial advisor debate isn’t about choosing one over the other permanently, but finding the right fit for your current financial situation – with the flexibility to adjust as your needs evolve.
Sources
Morningstar – Best Robo Advisors
Investing in the Web – Largest Robo-Advisors by AUM
Bankrate – Best Robo Advisors
NerdWallet – How Much Does a Financial Advisor Cost
Kitces – Vanguard Report on Robo vs Human Advisors
The robo-advisory landscape has dramatically evolved, with the market growing from $8.39 billion in 2024 to a projected $10.86 billion in 2025, making it crucial for investors to identify the best robo-advisors 2025 has to offer. These AI-powered investment platforms now combine sophisticated algorithms with personalized features, creating opportunities for both beginning investors and seasoned portfolio managers to build wealth efficiently through automated strategies.
Key Takeaways
- The robo-advisory market is experiencing explosive growth with a projected 30.3% CAGR through 2032
- Top platforms like Wealthfront and Betterment offer significant fee advantages (0.25%-0.89%) compared to traditional advisors (1-2%)
- ESG investing options and tax-loss harvesting have become standard features among leading robo-advisors
- Hybrid models combining AI algorithms with human CFP oversight represent the fastest-growing segment
- Minimum investment requirements vary widely from $100 (Vanguard) to $5,000 (Schwab), making accessibility a key differentiator
The Robo-Advisory Revolution: Market Growth and Trends
The robo-advisory industry is experiencing remarkable expansion, with the market size increasing from $8.39 billion in 2024 to an estimated $10.86 billion in 2025. This growth trajectory shows no signs of slowing, with a projected compound annual growth rate (CAGR) of 30.3% through 2032, according to Fortune Business Insights. The COVID-19 pandemic actually accelerated adoption, with a 13% surge during this period as investors sought digital solutions.
Several key factors are driving this explosive growth. The increasing demand for ESG (Environmental, Social, Governance) investing options has pushed most major platforms to incorporate sustainable portfolios. Hybrid advisory models that combine AI algorithms with human certified financial planners have gained significant traction, with 40% of firms now offering this blended approach. Automated tax optimization has also become a standard feature, attracting investors looking to maximize after-tax returns.
Assets under management (AUM) tell a compelling story about market leaders. Vanguard Digital Advisor has amassed approximately $19 billion by mid-2024, while Fidelity’s overall platform manages a staggering $15.1 trillion in client assets. These figures demonstrate the growing trust investors place in automated investment management tools.
How Robo-Advisors Stack Up Against Traditional Investing
When comparing performance metrics, there’s a noticeable trade-off between pure returns and risk management. In 2024, the S&P 500 delivered impressive gains of approximately 25%, while top robo-advisors generated average returns between 18-20%. This performance gap reflects the more diversified approach that most robo-advisors take compared to an all-equity index.
Looking at longer time horizons, Vanguard’s balanced 60/40 portfolios delivered 4.01% over 5 years, compared to the S&P’s 10.2% annualized return during the same period. However, the fee advantage of robo-advisors creates significant value over time. Most platforms charge between 0.25% and 0.89% of assets under management, compared to the 1-2% typically charged by human financial advisors.
This fee difference creates substantial savings. For a $50,000 portfolio, investors might pay around $125 annually with a robo-advisor versus $500 or more with a traditional advisor, according to Mezzi’s cost comparison analysis. The cumulative impact of these savings over decades can add hundreds of thousands of dollars to retirement portfolios.
The key consideration for investors is whether the automated approach to financial planning with built-in diversification and risk mitigation justifies potentially lower returns compared to passive index investing. For many, especially those who might otherwise make emotional investment decisions, the answer is yes.
Wealthfront: AI-Powered Tax Optimization
Wealthfront has established itself as a leader in the robo-advisory space with a competitive fee structure of 0.25% and a relatively accessible $500 minimum investment requirement. While its 2024 equity portfolio return of 18.07% trailed the S&P 500, this reflects its diversified approach to risk management rather than a performance failure.
The platform’s standout feature is its sophisticated tax-loss harvesting algorithm, which automatically identifies opportunities to offset capital gains with losses, potentially adding up to 0.5% in annual after-tax returns according to Investopedia. This feature becomes increasingly valuable as portfolio size grows, making Wealthfront particularly attractive for investors with larger taxable accounts.
Additional compelling features include:
- ESG investment options for socially conscious investors
- FDIC-insured cash accounts with coverage up to $1.25 million
- Customizable portfolio allocations based on risk tolerance
- Automated rebalancing to maintain target allocations
The cost advantage compared to traditional advisors is substantial. While a human advisor might charge 1-2% of assets annually, Wealthfront’s 0.25% fee translates to significant long-term savings that compound over time, especially for larger portfolios where the absolute dollar difference becomes considerable.
Betterment: Sustainable Investing Leader
Betterment offers a tiered pricing model with a standard plan at 0.25% AUM or $4/month, and a Premium plan at 0.65% for balances over $100,000. The platform’s 2024 performance highlights include an impressive 18.64% return for its Climate Impact SRI (Socially Responsible Investing) portfolio, positioning it as a leader in the sustainable investing space.
In 2024, Betterment restructured its fee system and introduced a Preferred Rewards program offering 0.25% APY boosts on cash reserves. This move strengthened its competitive positioning in the increasingly crowded robo-advisory market. The platform’s focus on climate-conscious investing aligns with broader industry trends, as approximately 70% of top robo-advisors now offer ESG portfolio options.
Key features that distinguish Betterment include:
- Highly customizable ESG portfolios with multiple themes
- Integrated cash management tools with competitive interest rates
- Access to certified financial planners for complex questions
- Goal-based investing frameworks for specific financial objectives
Betterment’s emphasis on sustainable investing has positioned it well to capture the growing segment of investors who prioritize environmental and social factors alongside financial returns. This alignment with evolving investor preferences has contributed significantly to its continued growth in the robo-advisory space.
Fidelity Go and Vanguard Digital Advisor: Established Players
Fidelity Go brings the reputation of a financial services giant to the robo-advisory space with an all-in fee of 0.35%, which is waived entirely for balances under $25,000. The platform delivered a solid 17.78% return in 2024 and maintains a respectable 4.17% five-year trailing yield. This performance reflects Fidelity’s balanced approach to portfolio construction.
Vanguard Digital Advisor has positioned itself as a low-cost leader with a net advisory fee of just 0.15%. In a significant move to improve accessibility, Vanguard reduced its minimum investment requirement from $3,000 to $100 in 2024, according to a corporate press release. While its five-year trailing return of 4.01% may seem modest, this reflects its conservative approach to risk management.
Both platforms benefit from their hybrid approach, combining automated algorithms with human oversight. This represents a key advantage over pure robo-advisors when markets experience unusual volatility. Morningstar’s 2025 rankings highlighted the ESG integration capabilities of both platforms as standout features.
Additional notable features include:
- HSA (Health Savings Account) integration for tax-advantaged medical savings
- Automatic rebalancing to maintain target allocations
- Access to broader ecosystem of financial products
- Extensive educational resources for investors
The backing of established financial institutions provides an additional layer of trust for investors who may be hesitant about newer fintech startups, making these platforms particularly attractive to first-time robo-advisor users.
Zero-Fee Options: Schwab Intelligent Portfolios and Alternatives
Schwab Intelligent Portfolios has disrupted the robo-advisory market with its $0 management fee model, though it requires a higher minimum investment of $5,000. The platform’s conservative portfolios maintain impressively low expense ratios averaging just 0.04%, further enhancing the cost advantage for investors.
Special features become available at higher balance thresholds. Tax-loss harvesting activates at $50,000, and the platform provides 24/7 advisor access for complex questions. However, investors should consider the cash allocation structure, which maintains a significant portion of portfolios in cash earning a 0.15% sweep rate – potentially creating a performance drag in strong equity markets.
Other low-cost leaders like M1 Finance also offer 0% AUM fees, generating revenue instead through premium subscription services and cash management. This represents a significant shift in the business model for automated investment platforms, prioritizing scale and ancillary services over direct management fees.
The zero-fee approach comes with important considerations:
- Higher minimum investment requirements may limit accessibility
- Revenue generation through cash allocations or premium services
- Potential limitations on portfolio customization
- Trade-offs between visible and hidden costs
For investors with sufficient capital who prioritize minimizing explicit costs, these platforms offer compelling value propositions, though careful analysis of the total cost structure remains important.
AI Innovation in Wealth Management
The integration of advanced AI techniques is rapidly transforming robo-advisory capabilities. Genetic algorithms are now improving portfolio returns by up to 30% through real-time behavioral analysis, according to research from NeoSoft Tech. These systems adapt allocation strategies based on market conditions far more dynamically than earlier generation robo-advisors.
Climate-focused portfolios have become mainstream, with 70% of top robo-advisors now offering these options. The sophistication of these offerings has evolved substantially, with granular screening criteria and impact measurement tools becoming standard features rather than simple exclusionary approaches.
Tax-loss harvesting automation has also evolved significantly. Modern platforms don’t just identify tax-loss opportunities but optimize the timing and execution of these strategies based on individual tax situations and market conditions. Research by Giovanni Falsetti demonstrates how AI personalization capabilities can now account for both financial goals and psychological factors in portfolio construction.
Looking ahead, the integration of predictive
AI is revolutionizing financial planning with accessible tools that make investing approachable for everyone, regardless of experience or wealth. The robo-advisory industry has exploded to nearly $92 billion in 2025, offering automated investment solutions that combine sophisticated algorithms with user-friendly interfaces for beginners seeking financial guidance.
Key Takeaways
- Robo-advisors manage nearly $92 billion globally in 2025, projected to reach $468 billion by 2029
- Beginning investors can start with as little as $0-500 compared to traditional advisors’ high minimums
- Annual fees average 0.25%-0.89%, saving investors up to 80% compared to human advisors
- AI-powered platforms automatically handle portfolio rebalancing, diversification, and tax-loss harvesting
- Ideal for simple financial situations but limited for complex needs like estate planning
The Robo-Advisory Revolution: What Beginners Need to Know in 2025
The financial landscape has transformed dramatically with AI financial planning for beginners becoming mainstream. Robo-advisors have created a true democratization of investing, removing barriers that once kept financial guidance exclusive to the wealthy.
The numbers tell a compelling story. The global robo-advisory market, valued at $91.97 billion in 2025, is projected to reach an astonishing $468.49 billion by 2029. This represents a compound annual growth rate of 50.2% through 2032, according to Fortune Business Insights.
North America currently dominates with approximately 45% market share, driven by high fintech adoption rates. Meanwhile, the Asia-Pacific region is growing fastest with a projected 29% CAGR, fueled by rapid digitalization and an expanding middle class in countries like India and China.
This explosive growth stems from a fundamental shift in how people access financial advice. Automated platforms have made investing accessible to everyone, not just those with substantial assets or specialized knowledge.
How AI Powers Your Financial Future: Understanding Robo-Advisor Technology
Behind every robo-advisor lies sophisticated AI technology that handles complex financial decisions automatically. These platforms implement Modern Portfolio Theory to build diversified portfolios primarily consisting of ETFs and index funds.
One key feature is automated rebalancing, which occurs quarterly or during significant market shifts. This ensures your asset allocation stays aligned with your goals without requiring manual intervention. Many platforms also offer tax-loss harvesting – a technique that minimizes capital gains taxes by strategically selling investments at a loss to offset gains elsewhere.
Risk profiling stands as another crucial AI application. When you sign up for a robo-advisor, you’ll complete a questionnaire covering factors like:
- Emergency fund status
- Home ownership
- Income stability
- Investment timeline
- Financial goals
Machine learning algorithms continuously refine these risk assessments as your financial situation evolves. For example, Plum’s savings algorithms analyze spending patterns to automatically set aside appropriate amounts based on your habits.
Natural language processing powers the interactive features that make these platforms user-friendly. Cleo’s chatbot represents this technology in action, allowing users to query their finances conversationally rather than navigating complex menus.
Top Robo-Advisors of 2025: Comparing the Market Leaders
Several platforms have emerged as leaders in the AI financial planning space, each with unique strengths. Here’s how they compare:
Vanguard Digital Advisor stands as the largest by assets under management (AUM) at $289 billion. It charges a 0.15% fee for balances over $3,000 and offers a hybrid option for those wanting occasional human guidance.
Schwab Intelligent Portfolios manages $65.8 billion AUM with zero management fees for its basic plans, making it attractive for cost-conscious investors. This fee structure is offset by a cash allocation requirement within portfolios.
Betterment has built a reputation for user-friendly interfaces with $26.8 billion AUM. Its fees range from 0.25% for the Digital plan to 0.40% for Premium, which includes access to human advisors for complex questions.
Wealthfront focuses on tax-efficient indexing and offers unique features like 529 college savings plans. With a 0.25% fee and $500 minimum investment, it balances accessibility with sophisticated features.
For micro-investors, budget options include Acorns with its $1/month subscription model and M1 Finance offering zero fees for portfolios under $10,000.
Cost Comparison: Why Robo-Advisors Are Winning the Fee War
The cost difference between robo-advisors and traditional financial planning is stark. While robo-advisors typically charge 0.25%–0.89% annually, human planners command fees of 1%–2% or more.
This translates to significant savings over time. Consider a $50,000 portfolio that costs just $125 per year with a typical robo-advisor charging 0.25%, compared to $500 annually with a human advisor charging 1%.
Some platforms have introduced hybrid models that combine AI efficiency with human expertise. Personal Capital exemplifies this approach, charging 0.89% for a service that blends algorithmic portfolio management with access to financial advisors.
Robo-advisors achieve these lower costs by automating labor-intensive tasks like:
- Portfolio rebalancing
- Tax-loss harvesting
- Market monitoring
- Investment selection
Perhaps most importantly, these platforms have dramatically lowered the entry barrier. You can start investing with $0–$500 depending on the platform, compared to the $250,000+ minimums often required by traditional financial advisors.
Advantages and Limitations: What AI Can (and Can’t) Do for Your Finances
Robo-advisors excel in several areas that make them ideal for beginners. They make bias-free decisions that avoid emotional trading, provide 24/7 portfolio monitoring, and execute real-time market adjustments without human intervention.
However, they do have limitations. These platforms struggle with complex scenarios like estate planning, business succession, or niche investments. They also can’t address the psychological aspects of investing that sometimes require human reassurance during market volatility.
Regulatory considerations are evolving with the industry. The SEC’s 2024 rule requires robo-advisors to operate “exclusively online” to maintain certain exemptions, as noted by ACAG Global.
Robo-advisors work best for:
- Beginning investors learning the basics
- Individuals with straightforward financial situations
- Long-term passive investing strategies
- Those comfortable with digital-only interactions
They’re less suitable for high-net-worth individuals with complex tax situations, those requiring detailed estate planning, or investors seeking highly specialized investment opportunities.
AI Innovation in Personal Finance: Beyond Basic Investing
The AI revolution extends beyond investment management into broader financial planning. Predictive budgeting apps like Rocket Money now forecast spending patterns by analyzing your transaction history, helping prevent cash flow problems before they occur.
Sustainable investing has become mainstream, with many platforms now prioritizing ESG (Environmental, Social, and Governance) portfolios. Wealthfront’s climate-focused ETFs exemplify this trend, allowing investors to align their values with their financial goals.
Voice-enabled planning represents another frontier. NLP tools in apps like Wally can analyze receipts via photo scans, automatically categorizing expenses without manual input.
Self-directed investing platforms increasingly incorporate AI guidance, providing suggestions without taking full control. Robinhood’s acquisition of Pluto AI has enhanced their predictive portfolio analytics, offering insights while leaving final decisions to the user.
These innovations make the financial planning process more intuitive and less intimidating for beginners, removing the technical barriers that once made investing seem inaccessible.
Getting Started with Robo-Advisors: Your 2025 Action Plan
Ready to begin your AI-powered financial journey? Here’s a straightforward action plan:
Step 1: Assess your risk tolerance using tools like SigFig’s questionnaire. Be honest about your comfort with market fluctuations and investment timeline.
Step 2: Compare platforms based on your priorities. If minimizing fees is most important, consider Schwab Intelligent Portfolios. If you value customization features, Betterment or Wealthfront might be better matches.
Step 3: Start with an appropriate minimum investment, typically ranging from $0-500 depending on your chosen platform. Many allow you to begin with small amounts and increase contributions over time.
Step 4: Monitor performance through comprehensive dashboards available in tools like Personal Capital or Mint. These provide a holistic view of your financial progress.
Before selecting any platform, clarify your financial goals. Are you saving for retirement, a home purchase, or education? Different robo-advisors excel at different objectives, so matching your needs to the right platform is crucial.
Remember that even with AI assistance, successful investing requires patience. The projected market CAGR suggests strong long-term growth potential, but short-term fluctuations are normal and expected.
Sources
Fortune Business Insights – Robo Advisory Market
Research And Markets – Robo Advisory Market Report
Investopedia – Robo Advisor Definition
Financial Advisor Transitions – Top 10 Roboadvisors by AUM
Mezzi – Robo Advisors vs Human Financial Planners Cost Comparison