Selling pressure in cryptocurrency occurs when a significant number of investors decide to sell their holdings, often due to factors like market uncertainty, negative news, profit-taking, or changes in regulations. This surge in sell orders increases the supply of the cryptocurrency on exchanges, outpacing the demand, and causing prices to drop. The fear of further decline can trigger more selling, creating a cycle where the value of the cryptocurrency continues to fall until the selling pressure stabilizes or reverses due to renewed buying interest or positive market developments.