JP Morgan/Jamie Dimon is worried:

It seems that JP Morgan is suggesting there's been a dangerous tailwind behind recent market price movement due to short-sellers covering shorts
markets.businessinsider.com - Stock market outlook short selling record lows correction volatility jpmorgan

The embedded chart shows the percentage of shorts (as fraction of shares outstanding) over time.
- From 2018-2023 or so short interest fluctuated around 15% as percentage of shares outstanding in SPY, and about 12% as percentage of shares in QQQ.
- From 2023 to now short interest has dropped to roughly 8% for SPY and 7% for QQQ.

SPY price has risen 46%, QQQ price has risen 88% percent, over 2023-present (non-annualized). Do you think value has risen that much?

In a different post, Jim noted that VIX1Y (the one year VIX, as opposed to the familiar one month VIX) is at quite low levels and so long-term options (depending on the underlying) should be relatively cheap. He suggested perhaps buying long-term quite OTM (hence cheap) puts on a short-list of highly over-valued firms.
Any suggestions for such firms?

Failing that, perhaps buying some long-term far OTM puts on QQQ would be an easy way to approximate that idea.
Hmmm... or perhaps buy puts on just the top five highest flyers in terms of price and P/E. Selling the appreciated puts would generate cash in a crisis which could be deployed to buy e.g. BRK, that has probably fallen with the market ("in a crash, correlations tend to 1.0").

Jamie Dimon has also recently been expressing concern about the fragility of markets due to (1) financial issues (e.g. interest rates perhaps higher for longer than anticipated) and (2) geopolitical issues (the usual list). Sorry, no link, just google him on youtube. When he gets concerned, I get concerned.