It seems Saylor's MicroStrategy has a total of 152,333BTC. That's around 0.73% of the entire Bitcoin supply, which makes MicroStrategy the largest company owner of Bitcoin. However, if I'm not mistaken, this doesn't even count those coins that its owner, Michael Saylor, personally owns. There were news in the past that Saylor has his own personal Bitcoin stash, of course much smaller than his company's.
It seems like a couple of years ago he was owning 17,732 BTC while the company owned 114,042 coins:
MicroStrategy CEO Michael Saylor reveals personal BTC holdings
The article is written a year ago and references a Saylor tweet from October of the previous year, so we can assume that just as he has continued to accumulate Bitcoin for MSTR, he will also have continued to increase his personal holdings.