Offer your thoughts or opinion on the input financial query or topic using your financial background.

Is the money you get from shorting a stock free to use for going long on other stocks?
You sold $10,000 worth of stock so that money is essentially yours.  However, you sold this stock without actually owning any which means that you, through your broker, are currently borrowing shares amounting to (at the time of your sale) $10,000 from someone who actually owns this stock. You will be paying this person interest for the privilege of borrowing their shares, the exact amount charged varies wildly and depends on factors such as short interest in the stock (loads of people want to go short = shareholders can charge high interest) etc. If I remember correctly hovering over the "position" column in your portfolio in the IB Workstation should give you information about the interest rate charged.  You will have to buy back these shares from the lender at some point which is why the $10k isn't just "free money." If the stock has gone up in price in the meantime you are going to be paying more than the $10k you got for the same amount of shares and vice versa.