Netflix Inc. investors have punished the company for its shock loss in subscribers and abrupt turnabout to embrace advertising after years of shunning it.

Shares of the streaming leader plunged 35%, erasing $54 billion of market value in its biggest drop since 2004. The swoon made Netflix the worst-performing stock of the year on both the benchmark S&P 500 and Nasdaq 100 indexes and sent shock waves across the media universe, sinking Warner Bros. Discovery Inc., Roku Inc. and others.

Netflix is seeking ways to stop a loss of subscribers and combat investor fears that its best days are over. Co-founder Reed Hastings had said for years that he doesn’t want to offer advertising and had no problems with password sharing.