Several theories from Derek Thompson
https://stocks.apple.com/AntZ_5XKvTfCWKfQF5MvzNQ1. Companies thought the pandemic was an accelerant to the economy of 2030 but it was a bubble
2. Interest rates punish companies with high P/E based on future growth.
3. My favorite. “Tech” companies are really advertising companies for the most part and advertising takes big hits in turndowns
4. Social contagion. CEOs see other companies lay people off and see stock price boom, so they think they should lay people off too. Many of these companies laying people off are profitable, but they want to keep stock prices high too