Blackrock manages the iShares Biotechnology ETF (IBB). It has 9% moderna, 4.35% Biontech. So every time they buy shares, they buy more than 2 shares of moderna for every share of
bntx. So why is Blackrock doing this when Biontech has fda approval, possibly all approvals till now, has more revenue, profits, eps, and no news of manufacturing/supply issues, no bans in Europe and no insiders selling as often as mrna insiders? The reason may be none of those things. Moderna is an American company, has more shares (400m vs 240m of bntx) and offers more liquidity for trading. Can blackrock update their holdings to have more bntx in future? There's nothing stopping them. It may be end of qtr or end of the year but no one really knows when that may happen. Also read elsewhere bntx may be included in nasdaq 100 in December.

$BioNTech SE(BNTX)$ $Moderna, Inc.(MRNA)$