An emergency fund is money you may need liquid, not money you know you need to spend. Having one is equivalent to setting a portion of your portfolio's volatility to 0. If your portfolio size is large enough, you can view the emergency fund from a risk management perspective to optimize your expected return. An emergency fund in a high yield savings account is meant to cover a certain amount of liquidity at the price of your expected returns. But the liquidity risk gets smaller and smaller the larger your portfolio is relative to your expenses, so it's better to retain those higher expected returns by keeping your funds in the market. This is especially true if you have access to margin (with margin rates lower than expected return of the market) and you aren't pressured to sell your stocks at losses.