Grayscale Investments CEO Michael Sonnenshein argued that U.S. regulators were "discriminating" against his cryptocurrency investment firm by continuing to deny approval to exchange traded funds based on the spot price for Bitcoin (BTC-USD).The comments followed news that Grayscale had filed suit against the U.S. Securities and Exchange Commission after the regulatory body denied the firm's application for a Bitcoin ETF."The SEC is acting arbitrary and capricious by continuing to approve Bitcoin futures ETFs while continuing to deny spot Bitcoin ETFs," Sonnenshein told CNBC.The CEO of Grayscale, which operates the Grayscale Bitcoin Trust (OTC:GBTC), assured investors that the company was fully committed to pursuing its legal options to force an eventual SEC approval."We are not going to stop. We're going to put the full resources of the firm behind this lawsuit," he said.Calling the SEC's decision "an unbelievably missed opportunity," Sonnenshein argued that approving a spot Bitcoin ETF would help build a safer regulatory framework around the cryptocurrency market, ultimately providing more protections for investors."A U.S. regulator is shunning the opportunity to bring this further into the regulatory perimeter and give investors more disclosure, more protections," he contended.While Grayscale has long pursued approval for its Bitcoin ETF, the latest developments come at a sensitive time for the crypto market. Bitcoin (BTC-US...