Verbal Offer-----> Written Offer

Unfortunately not. Had this happen to a friend and after 3-4 weeks the firm told him they changed their mind about hiring at all. Not him but the role/need. 

On the real life scale, like HFPM pointed out, it's not entirely unusual so don't spiral out thinking you done messed up somehow. I mean they're keeping up with your regular contacts aren't they?

We can get into the legal BS later. Just saying a verbal committment is still valid, albeit the written offer is stronger, etc.

As someone on the other side, there are a lot of steps that happen after the acceptance of a verbal offer. Typically there are hiring committees/ approvals, reference checks, background checks, etc. These can easily take up to a month. If you have no red flags that would come up in any of these processes then I wouldn’t worry. 

If you want to create some urgency, pretend you have an alternative offer and tell these guys they are your preferred option but you can't be waiting around forever.

Of course you are bluffing and need to get comfortable with the risk, but over a month is too much and they might be playing games with you.

Hey sorry to hear this is happening to you. I was in the same situation last year and found out after 2 months or so that the PM was blown out and let go. Felt like shit at the time but in hindsight I dodged a bullet. 

I was at the verbal offer stage but no reference or background checks were done. Did those happen for you already?

Call the hedge fund's HR.  They can usually pinpoint what is holding up the offer and you can work with them to fix it.