Someone announces that they will invest $400 million in BTC and the price of the same loses more than 6% - some would say that this is just a normal correction after we have already determined that there is strong resistance on $19500 - but some who believe in crypto market manipulations could say that someone (in this case Coinbase) allows their client (MicroStrategy) to get more BTC for their money.
Of course, something like this could be classified as conspiracy theories, but in the last purchase, Coinbase publicly boasted that it had saved its client as much as $4.25 million by using
advanced trading tools. Either way the timing for the purchase is well-balanced no matter why the price has dropped - if MS saves just $1000 per one BTC purchased, it will be a good buy again.