Certainly possible, but they would have had to be holding in the first place to cause this mess.
If factions of the financial establishment is interested in adopting Bitcoin, probably they procure their coins direct from miners. Probably, the price is based upon the Bitstamp spot price. If this is the case, probably, the vast majority of the volume of Bitcoin trade is conducted over the counter. If this were so, then it would be very easy for a whale entity with deep enough pockets, to deliberately smash the exchange price lower, and generally use their buying power to inflict a long term bear market technical scenario on the exchange determined Bitcoin market. This would force the price down that the miners could ask for their coin. Perhaps, they can drive Bitcoin down so low, that the miners would be put out of business, or be forced to sell their mining operations to the whale entity for pennies on the dollar (the whale would be the only buyer, because only the whale with inside knowledge would know that they weren't buying a dead dodo). If this were all to be the case, then the whale entity could take a massive controlling stake in existing Bitcoin shares, and in the mining of future Bitcoins. At the point that they have taken a position which is to their liking, they could use their own capital to start engineering the price of Bitcoin upwards once again, eventually allowing Joe Public and then mainstream investment funds to enter into the market via ETF products or otherwise, resulting in Bitcoin being driven into the stratosphere, whilst the whale sits backs and enjoys glittering profits for all their groundwork and perhaps even comes into a position of significant political power as a result of their massive controlling stake in the Bitcoin algorithm.
This may sound fantastical but probably wouldn't be all that hard to do, if a department of a financial institution that had access to literally unlimited supplies of cash or 'credit', that wanted to muscle into Bitcoin.
I wouldn't rule it or something else like it out. There are plenty well documented examples of much more devious financial shenanigans than what I have described, and in much more massive and politically important markets than Bitcoin.