When you open a short position, you sell shares and receive money. A market short-sale order generally fills at the highest available bids, which are the prices buyers offer. Ask prices are what sellers want. The $2.50 last-sale price records the previous trade and does not guarantee the price you'll receive. [Investor.gov: Types of Orders](https://www.investor.gov/introduction-investing/investing-basics/how-stock-markets-work/types-orders)

Opening and closing a short involves three steps:

1. Your broker arranges for you to borrow shares. You owe the lender those shares back, or 1,000 shares in your example. You aren't buying them from the lender at $2.50. Borrowing fees and collateral requirements are separate from the sale price.
2. You sell the borrowed shares to buyers through your short-sale order.
3. Later, you buy shares back and return them to the lender to close the short. Your trading profit or loss is the sale proceeds minus the repurchase cost, before fees and other costs. [SEC: Short Selling and Regulation SHO](https://www.sec.gov/investor/pubs/regsho.htm)

To work out what you might receive in your example, we need the bids. The ask prices alone don't tell us. Suppose buyers are offering:

| Buyers' bids | Shares available | Your sale proceeds |
|---|---:|---:|
| $2.50 | 500 | $1,250 |
| $2.40 | 250 | $600 |
| $2.00 | 250 | $500 |
| Total | 1,000 | $2,350 |

If those bids remain available, no better prices appear, and no short-sale restriction applies, your market order could fill in those amounts for an average sale price of $2.35. You wouldn't automatically receive the first price for all 1,000 shares.

Your original ask ladder, with 500 shares at $3, 250 at $3.50, and 250 at $4, matters when buying shares, including buying to close a short. Under the same assumptions, buying all 1,000 shares would cost $3,375, or an average of $3.375 per share. A limit order lets you set a minimum selling price or maximum buying price, though some or all of the order may go unfilled. [Investor.gov: Order Execution](https://www.investor.gov/introduction-investing/investing-basics/how-stock-markets-work/types-orders)

How often you might be unable to short depends on the stock, the quantity you want, your broker's lending supply, and your account eligibility. There is no useful universal frequency. Your broker may have no shares to lend, too few to fill your order, or restrictions on that stock. Even when shares are available, borrow fees can make the short expensive. [Schwab: Short-Sale Terms](https://advisorservices.schwab.com/legal/schwab-one-account-agreement)

U.S. rules also restrict short-sale prices after a covered stock falls at least 10% from its previous closing price. For the rest of that day and the following trading day, short sales generally cannot execute at or below the national best bid, subject to exceptions. This can prevent immediate execution even when shares are available to borrow. [SEC: Rule 201](https://www.sec.gov/rules-regulations/staff-guidance/trading-markets-frequently-asked-questions-7)