Cardano's ADA cryptocurrency has plunged by 23% in the last 24 hours, amid fears of a clash with the U.S. Securities and Exchange Commission (SEC). The sharp drop comes after the SEC filed a lawsuit against Coinbase, suggesting several altcoins, including ADA, could be classified as securities. This has led to almost $400 million in market liquidations. However, Input Output Global, the firm behind Cardano's ecosystem, has refuted these claims, insisting that ADA is not a security in a recent blog post. The rest of the altcoin market is also experiencing significant downturns.