I work in quant trading - I can guarantee you at least 4/7 of the firms on that list are well-known, well-respected, and would count as "big funds". Can't comment on the actual pods that apparently went bust though, but generally you should expect the average pod at these places to be at least reasonably good considering the sink-or-swim environment they are perpetually in.
Pods can go broke on a 4% _rise_ in the stock market. They make levered bets and it's easy to get way on the wrong side of one.