(Bloomberg) -- Robinhood Markets Inc. is cooperating with an investigation from New York’s top law enforcement office into “brokerage execution quality,” the retail trading firm said in a regulatory filing.Most Read from BloombergUS Bank Shares Drop as Moody’s Cuts Ratings, Warns on RisksWall Street WhatsApp, Texting Fines Exceed $2.5 BillionMusk Says He May Need Surgery, Will Get MRI on Back and NeckThe Global South Breaks Away From the US-Led World OrderBillionaire Desmarais Family Quietly Res