S&P 600 (small caps) is down 25%
S&P 400 (midcaps) is down 24% YTD
Equal Weighted S&P 500 is down 21%
By quick check, during the worst 14 day stretch of Sep/Oct 2008, 9/20-10/9:
Smallcap -31%
Midcap -32%
Eq Wt SPX -30%
The difference with the GFC is 1) existential banking collapse 2) how long it persisted