Coca-Cola. Berkshire Hathaway. Marriott. Philip Morris. Walmart.These are just some of the companies whose debt was snapped up by the Federal Reserve as of mid-June, part of the central bank’s unprecedented intervention in credit markets. CNN parent company AT&T is another.What’s happening: The Fed disclosed hundreds of millions of dollars in purchases of individual corporate bonds on Sunday, while identifying nearly 800 eligible issuers whose bonds it could buy down the line.The action by the Federal Reserve has been lauded by investors for easing conditions in credit markets after they rapidly deteriorated in March, avoiding a potentially catastrophic corporate cash crunch that could have triggered a wave of bankruptcies.