what is a buy in 
a buy in in the financial markets is an occurrence in which an investor is forced to repurchase shares of security because the seller of the original shares did not deliver the securities in a timely fashion or did not deliver them at all a buy in can also be a reference to a person or entity buying shares or a stake in a company or other holding in psychological terms the buy in is the process of someone getting on board with an idea or concept that is not their own but nonetheless appeals to them understanding buy insthose who fail to deliver the securities as promised are generally notified with a buy in notice a buyer will send notice to exchange officials as a result officials will usually notify the seller of their delivery failure the stock exchange e g nasdaq or nyse supports the investor in buying the stocks a second time from another seller typically the original seller must make up any price difference between the original price of the stock and the second purchase price of the stock by the buyer failure to answer the buy in notice results in a broker buying the securities and delivering them on the client s behalf the client is then required to pay back the broker at a pre determined price the difference between a buy in and a forced buy inthe difference between a traditional and forced buy in is that in a forced buy in shares are repurchased to cover an open short position a forced buy in occurs in a short seller s account when the original lender of the shares recalls them this can also occur when the broker is no longer able to borrow shares for the shorted position in some cases an account holder might not be notified before a forced buy in a forced buy in is the opposite of forced selling or forced liquidation settlement of securitiessecurities transactions typically settle in t 2 business days following the transaction t 0 which applies to the majority of securities such as stocks and corporate bonds some transactions have a settlement of t 1 business day while others can even settle on the same day as the trade date same day transactions are called cash trades in the above transactions the trades will settle according to their respective settlement dates however if the securities fail to be delivered a buy in will occur 