Segregated stocks can be lent out with your permission and as you increase leverage the number of shares segregated will likely go down and hence available shares to lend out as part of the SYEP. The paste below explains eligibility better than I do above. Hope it helps. I should also, add the amount lent out will also depend on the availability and demand of shares. Harder to borrow stocks are more likely to be lent out given supply/demand. https://ibkr.info/article/1838 How does IBKR determine the amount of shares which are eligible to be loaned? The first step is to determine the value of securities, if any, which IBKR maintains a margin lien upon and can lend without client participation in the Stock Yield Enhancement Program. A broker who finances client purchases of securities via margin loan is allowed by regulation to loan or pledge as collateral that client’s securities in an amount up to 140% of the cash debit balance. For example, if a client maintaining a cash balance of $50,000 buys securities having a market value of $100,000, the debit or loan balance will be $50,000 and the broker holds a lien on 140% of that balance or $70,000 of securities. Any securities held by the client in excess of that amount are referred to as excess margin securities ($30,000 in this example) and are required to be segregated unless the client provides IB the authorization to lend through the Stock Yield Enhancement Program. The debit balance is determined by first converting all non-USD denominated cash balances to USD and then backing out any short stock sale proceeds (converted to USD as necessary). If the result is negative then we free up 140% of that negative number. In addition, cash balances maintained in the commodities segment or for spot metals and CFDs are not considered.