Strategy's perpetual preferred stock, Stretch (STRC), is the fourth largest holding in BlackRock's iShares Preferred and Income Securities ETF with $210 million allocation. The ETF also holds several other Strategy preferred stocks including Strife (STRF), MSTR common stock, and Stride (STRD), totaling around $380 million in value. These allocations underscore Strategy's notable influence within the ETF's portfolio.