Logo of the Organization of the Petroleum Exporting Countries (OPEC) Andrey Rudakov | Bloomberg | Getty Images Hello, this is Katie Foley writing to you from London. The UAE's shock OPEC exit is rippling across markets. But there are a host of other currents at play for investors today - a slew of earnings, a raft of rate decisions and a sea change at the Fed. What you need to know today And finally... UAE’s departure from the OPEC oil cartel is not without precedence. Who could be next? The United Arab Emirates'  shock decision to leave OPEC  is reverberating across global energy markets, exposing fractures in the powerful oil cartel as production quotas risk prompting other members to follow suit. "The UAE exit is another chapter in the changing membership of the group," said Andy Lipow, president of Lipow Oil Associates.…