你有一线 info， 还是 draw conclusion based that chart?

# of employees increased a lot last few years so drawing conclusion based on that chart could be misleading. 

https://www.efinancialcareers.com/news/2023/09/jane-street-jobs 

I heard story that Jane st takes screening seriously (hiring cost up incuding intern training) so employee retention is good. Self claim: no kids working there. 

Quant Traders are only hired from intern (there could be old intern. One year Vanessa was on camp too

https://en.wikipedia.org/wiki/Vanessa_Selbst )

Citadel is known for "easier" hiring and famous for revolving door approach. Trader 5% (10%?) lay off per quarter based on performance but those laid off people have garden leave. Good balance.