A manipulative market practice (market abuse) whereby a thinly traded stock is accumulated, marketed and then sold artificially overpriced to unsuspecting or naive investors. Some fraudulent investors gather investment information from unreliable or unofficial sources, especially nowadays by way of internet chat rooms, and set on convincing inexperienced investors of buying from them. In pre-internet era, the boiler room was used similarly in trying to pump up the price of a stock only to sell it.

The opposite of pump and dump is poop and scoop (the former focuses on pushing the price up, whilst the other on driving it down).