Bid/Ask Spread
Definition
The bid/ask spread is the difference between the highest price a buyer is willing to pay for an asset (the bid) and the lowest price a seller is willing to accept (the ask). This spread represents a core component of trading costs, particularly for investors who frequently buy and sell securities.
Tight spreads typically indicate a liquid market with many participants. Wider spreads are common in illiquid markets or during periods of high volatility.
Why It Matters to Investors
- Represents an implicit cost every time you enter or exit a position
- Wider spreads can materially impact returns, especially for short-term traders
- Reflects market liquidity and investor interest in a particular security
- Spreads tend to widen in stressed or fast-moving markets
- Smaller investors may face higher spreads than institutional players
The TiltFolio View
Because TiltFolio Adaptive trades only once per month and TiltFolio Balanced rebalances annually, both systems exclusively use highly liquid ETFs where bid/ask spreads are generally minimal. These ETFs typically trade with penny-wide spreads during regular hours, especially when executed via market orders at the open or close.
While spreads are a critical concern for high-frequency or active traders, their impact on both TiltFolio systems' long-term, low-turnover strategies is negligible. Both systems are designed for efficient implementation with minimal slippage and transaction costs.
Real-World Application
• A large-cap ETF like SPY often has a spread of just $0.01 due to deep liquidity
• A thinly traded small-cap stock may have a $0.20 or larger spread, creating friction for investors
• Spreads widen sharply during market stress, making execution more expensive
• High-frequency trading firms often profit by capturing the bid/ask spread