By Hannah Lang, Suzanne McGee and Manya Saini (Reuters) – U.S.-listed bitcoin exchange-traded funds (ETFs) saw $4.6 billion worth of shares trade hands as of Thursday afternoon, according to LSEG data, as investors jumped into the landmark products approved by the U.S. securities regulator on Wednesday. The products mark a watershed moment for the cryptocurrency industry that will test whether digital assets – still viewed by many professionals as risky – can gain broader acceptance as an investment. Eleven spot bitcoin ETFs – including BlackRock’s iShares Bitcoin Trust, Grayscale Bitcoin Trus…