Shares of Marqeta, Inc. experienced a significant decline, plummeting over 40% following a disappointing earnings forecast for the fourth quarter. The payment card partner for companies such as Block and Affirm announced a substantial guidance cut, leading to a pre-market drop of 36.1%. Analysts attributed the stock's decline to a combination of factors, including a weak outlook that may result in the company losing a third of its value. In light of these developments, several law firms, including Glancy Prongay & Murray LLP and Kirby McInerney LLP, have initiated investigations into potential shareholder claims against Marqeta.