Cathie Wood's Ark Invest bought $21 million worth of Block Inc. (SQ) shares on Thursday, adding 267,676 shares across its ARKK, ARKW, and ARKF ETFs. The purchase came as Block's stock fell 6.15% to close at $79, following concerns raised by analysts about the company's rising operating expenses in Q2, despite reporting solid financial results and cutting 40% of its workforce in February.