I got a couple of months' gardening leave (as it's known in the industry). The most senior guys would typically get six months off work: three paid, three unpaid.
It's just an industry-standard way of doing things. I didn't leave for a competitor but still got a paid vacation (though in principle I was "on call" while I was on the books).
To be honest, it sort of felt like a courtesy they extended rather than a means of protecting their IP. There's already a huge amount of lateral hiring in asset management, so everyone already kinda-sorta knows what everyone else is doing.