This must be some strategy to balance the money they have, according to my knowledge this share that they have sold is also a BTC ETF but this is of the future not of Spot, and I suppose, the company might not have enough funds to meet the liquidation price for this future ETF and that's why they shifted from Future to spot one. Which is their own ETF ARKB.
How this can impact the market, I think BTC ETF in spot opened a new way for companies to manage their funds, to manage risk. This means, they are the ones who are getting most of the profit out of BTC ETF approval. There is another explanation to this, and that is, currently market is highly volatile due to the involvement of big whales, and it might be an indicator that if ARKs have moved there funds from future to spot then a dump might be coming from which they want to save there funds from liquidating.