Online brokers clamped down on retail investors’ bets on several highly popular but volatile stocks on Thursday, locking traders out of the market and drawing sharp criticism from some users and politicians.

Large US brokers, including Schwab and Robinhood, curbed trading in shares including the video game retailer GameStop, cinema chain AMC and tech pioneer BlackBerry, sending them all sharply lower. GameStop was down 44 per cent, for example, and AMC closed down 57 per cent.

After the market closed, Robinhood, the online app synonymous with the rise of the retail trader, wrote on its website: “We made a tough decision today to temporarily limit buying for certain securities. As a brokerage firm, we have many financial requirements, including SEC net capital obligations and clearinghouse deposits.”