I can only speak for my little corner of the market. For systematic trading, there's LinkedIn and there's efinancialcareers. Those are places where you find ads for the type of jobs I'm interested in.
But don't apply for the jobs on those portals, that is just a black hole. Just look at the ads, note down the names of the recruiters and firms they work for, and either phone them or message them on LinkedIn.
They'll have a chat with you to find out your situation, and then they will tell you what jobs they've got. Note that every recruiter in the whole world thinks they have a great relationship with Citadel, Millennium, and every other well known employer in the space, so those intros have no value at all to you, since anyone could be your gateway. They'll also have a bunch of less well known firms, so you need more than one recruiter since they don't all know everyone.
Of course LinkedIn is also a way for the recruiters to get in contact with you. Just set yourself to open and wait around, a fish comes every week or so.
Putting your resume on job boards for 3rd party recruiters (at least in India). Not sure how it is in EU/US.
For recruiters within a company, try looking for them on LinkedIn, check out a recent post of theirs to verify if they still work for the company, and reach out with an application if they have an email address, or via LinkedIn messages.
When I search for companies in India, all I get are 3rd party recruitment firms. The recruiters themselves are hopeless and ask questions like "How many years of Git experience do you have?".
How do you find promising companies in the first place?
But don't apply for the jobs on those portals, that is just a black hole. Just look at the ads, note down the names of the recruiters and firms they work for, and either phone them or message them on LinkedIn.
They'll have a chat with you to find out your situation, and then they will tell you what jobs they've got. Note that every recruiter in the whole world thinks they have a great relationship with Citadel, Millennium, and every other well known employer in the space, so those intros have no value at all to you, since anyone could be your gateway. They'll also have a bunch of less well known firms, so you need more than one recruiter since they don't all know everyone.
Of course LinkedIn is also a way for the recruiters to get in contact with you. Just set yourself to open and wait around, a fish comes every week or so.