A new crypto exchange backed by firms including Citadel Securities, Fidelity Digital Assets and Charles Schwab Corp. said it’s gone live, a move that could reshape the digital-asset landscape amid heightened US scrutiny of the sector. EDX Markets, an institutional-only exchange announced in September 2022, will offer trading in four cryptocurrencies: Bitcoin, Ethereum, Litecoin and Bitcoin Cash. Unlike existing crypto platforms such as Coinbase Global Inc. and Binance Holdings Ltd.,