There are a lot of small cap bio-techs with greater than 50% institutional ownership. It isn't like Insty's don't invest in these stocks. What are the "broad strokes" they are using that excludes NWBO, but includes a lot of other small and highly speculative companies?
That's why there are some very select hedge funds out there who only take around 100 clients, and only diversify into 40-60 companies, all very thoroughly vetted -Pyrrhonian
The 100 client limit is regulatory, not the choice of the hedge fund. That type of fund accepts funds primarily from Accredited Investors. (3(c)1 fund)
Other funds have a 500 client limit, they can only take funds from Qualified Purchasers, which is a much higher qualification threshold. (3(c)7)
The majority of funds are 3(c)1 and limited to 100 total investors.