Even 10% of stock market assets in one name is large unless you have other assets not subject to market risk.
A development stage biotech is subject to so many more risks than just market risk, holding them (after all they have no revenue) is much riskier, because they also have the other risks that every stock has, like Management Risk... and we got screwed with that one too.
There is also Financing Risk and PRH screwed us on that one, since this company has Going Concern warning in the SEC filings and is technically insolvent. Of course, much of the shareholders are oblivious to that risk, but fear reverse splits ,so they think they have won by the company being unable to raise enough equity all these years to step up the pace of research. Going forward, we can hope it will be different and new equity money will be invested (and cause the dreaded dilution).
A rational person has to expect a huge return to incur the risk of owning shares here... and from 7 cents, a huge % return is possible. I view this as a lottery ticket purchase.
I am waiting for the Big Draw.