7 Numbers to Know Before You Sell a Stock

Selling a stock is a decision with tax, portfolio, and financial implications that are easy to underestimate when the emotional pull of a gain or the anxiety of a loss is driving the decision. These seven numbers provide the analytical framework that produces better selling decisions than intuition alone.

1. Your Cost Basis
The cost basis is what you paid for the shares, including any commissions. It determines the gain or loss you realize when you sell, which determines the tax consequence. Selling shares acquired at different times for different prices means the cost basis varies depending on which shares are sold, and the accounting method used, FIFO, LIFO, or specific identification, affects the taxable outcome.

2. How to Profit From Stocks
SoFi's stock profit calculator calculates your actual profit from a stock sale by subtracting your cost basis and any applicable taxes from the sale proceeds. This gives you the real after-tax return rather than the gross gain, which is the number that actually matters for evaluating whether the sale produced the outcome you were seeking.

Understanding how to profit from stocks involves more than watching the price go up. It involves selling in a way that maximizes the after-tax proceeds and aligns with your broader portfolio strategy.

3. The Holding Period
Gains on assets held more than one year qualify for long-term capital gains tax rates, which are lower than short-term capital gains rates for most taxpayers. The difference between selling at eleven months and selling at thirteen months can be several percentage points of tax on the gain.

If a stock is approaching the one-year threshold, evaluating whether the tax benefit of waiting justifies the market risk of holding for the additional time is a worthwhile calculation.

4. The After-Tax Proceeds
The gross gain from a stock sale and the after-tax proceeds are different numbers, and the after-tax figure is the one that determines what you can actually do with the money after the sale. Short-term gains taxed at ordinary income rates can reduce the effective proceeds significantly compared to long-term gains.

5. Your Portfolio Concentration After the Sale
Selling stock in a single company that represents a large portion of your portfolio reduces concentration risk. Holding concentrated positions in employer stock or other single securities creates a risk profile that diversified portfolios do not carry, and the sale decision should account for what the portfolio looks like after the sale.

6. The Opportunity Cost of Selling
Every sale has an opportunity cost in both directions. Selling a winning stock means forfeiting any future gains if the stock continues to rise. Holding a losing stock in the hope of recovery means the capital is unavailable for other investments that may produce better returns.

7. Whether the Original Investment Thesis Still Holds
The best reason to sell a stock is that the reason you bought it no longer applies. A change in company fundamentals, management, competitive position, or market dynamics that undermines the original investment thesis is a genuine reason to sell. A change in price alone, up or down, is not.