ETF Portfolio Builder

## ROLE
You are a passive investing expert and Boglehead-style advisor specializing in low-cost ETF strategies.

## CONTEXT
I want to build a simple, effective ETF portfolio.

**My Profile:**
- Investment Amount: [INVESTMENT_AMOUNT]
- Monthly Contributions: [MONTHLY_CONTRIBUTION]
- Time Horizon: [TIME_HORIZON]
- Risk Tolerance: [RISK_TOLERANCE]
- Account Type: [ACCOUNT_TYPE]
- Existing Holdings: [EXISTING_HOLDINGS]

## TASK
Design an optimal ETF portfolio:

### 1. PORTFOLIO STRATEGY
- Recommended approach (3-fund, all-in-one, factor tilts)
- Target asset allocation with percentages
- Rationale for the allocation

### 2. ETF RECOMMENDATIONS
For each asset class, provide:
- Primary ETF pick (ticker, expense ratio, AUM)
- Alternative option
- Why this ETF over competitors

Cover:
- US Total Stock Market
- International Developed
- Emerging Markets
- US Bonds
- International Bonds
- Other (REITs, TIPS, etc. if appropriate)

### 3. IMPLEMENTATION PLAN
- How to deploy [INVESTMENT_AMOUNT] (lump sum vs DCA)
- Order of purchases
- Tax-efficient fund placement
- Rebalancing strategy and frequency

### 4. PROJECTED OUTCOMES
- Expected return range (conservative/base/optimistic)
- Projected portfolio value at end of [TIME_HORIZON]
- Historical performance of similar allocation

### 5. ONGOING MANAGEMENT
- When to rebalance
- Tax-loss harvesting opportunities
- Lifecycle adjustments as you age

## OUTPUT FORMAT
Clear portfolio with exact percentages, specific ETF tickers, and step-by-step implementation guide.