Margin debt was up to $600 Billion in Q4 of last year ... it has dropped down to a measely ~$575 Billion since then per a historical chart here:
FINRA numbers indicate it was up to $825 Billion in February - but has dropped to only $753 Billion as of May:
https://www.finra.org/investors/learn-to-invest/advanced-investing/margin-statistics
It’s ridiculously high - the data only goes back to ‘97
This site indicates that it’s near the most it’s ever been but not necessarily the worst when compared to the size of the market - this time the data goes back to 1970: https://www.currentmarketvaluation.com/models/margin-debt.php
Prior to the 2008 plummet it was close to 3% now it’s around 1.75% after peaking in Q4 around 2% of market cap. Still in line with where we were pre-dotcom bubble pop and too high in my opinion..but then all debt is IMHO so.....
Finally found information on the 20s indicating margin was as low as 10-20% down in the 20s, I know for me now it varies by stock but the lowest I’ve seen for the past few years was 35% down.
artcle: https://www.thoughtco.com/the-stock-market-crash-of-1929-1779244