(Bloomberg) -- US banks are starting to ramp up purchases of everything from mortgage-backed securities to collateralized loan obligations after nearly two years of cutting back, adding fuel to a multi-month rally across credit markets.Most Read from BloombergTrump, Sons and Associate Hit With $364 Million Fraud FineAlexey Navalny, Jailed Activist Who Defied Putin, Dies at 47Wall Street Ends Wild Week on Sour Note After PPI: Markets WrapHawaii Rightly Rejects Supreme Court’s Gun NonsenseApple Re