The act of purchasing something and then immediately or quickly selling it. Used frequently in reference to residential real estate speculators who buy, fix and resell single-family residences. Used frequently in reference to IPO's if investors purchase shares in the IPO because they want to sell into a spike in price on the first day of trading. To capitalize on this opportunity, the investor would buy and then almost immediately turn around and sell shares into the public market. An IPO investor who sells shares within 30 days after the shares first trade is considered a "flipper" by securities broker-dealers. Often the managing underwriters in an IPO require management and other significant stockholders to sign lock-up agreements. Pursuant to a lock-up agreement, the company's directors, officers and 1 to 2% or more stockholders agree not to sell shares concurrent with or immediately following an IPO. Under a lock-up agreement, the stockholders party thereto must refrain from selling their shares for a stated period of time following the IPO (usually, six to nine months).