I cannot confirm this. ~300k is pay (excluding sign-on) fresh out of college at a big HFT -- sufficiently senior devs make 7 figures.
I think an interesting target for comparison with big tech is Jane Street, since their culture and WLB are good, so the main QoL drawbacks of finance don't apply. A new grad will get ~300k at Jane Street, though probably not with this large a sign-on.
Jane Street, from what I recall, is 300K (base + bonus) and 125K sign-on, and also it is non-negotiable. No idea what their numbers are like for experienced hires from competitors.
Where I work at, the new grad offers are slightly better than FAANG, but the growth is very good based on performance, we also pay very well to people coming in from a competitor.
I can confirm, known firm, manager role, offer was $1,3M full cash.