^ Yes, there could be a risk on the market price because they holding a big amount that anytime they will sell it at once and may have an impact on BTC price. Big investors like big institutions are considered as also whales but they don't have regularly playing the market, the most afraid is when they are all the same in the mind of selling their BTC. I don't know what will happen if most of them believe in FUD and do panic selling, BTC price will probably crashing out that causes a sudden dump. Nevertheless, in my mind thinking that it is impossible to happen, we are already in the middle in the mainstream, and BTC price keep growing.
I don't think it possible for institutions or whales to dump their bitcoin, otherwise it's a fake news. Bitcoin is the mainstay in cryptocurrencies and definitely lucrative. they store as many bitcoin as they can to achieve wealth accumulation and we should learn from them. risk lies primarily in altcoins, not bitcoin.
anyway, I'm a devour bitcoin believer and I won't let my bitcoin go. I don't care whether it's risky for institutions to hold it.