Merck ( MRK ) , for example, has rallied nearly 50% since October 2011, and its yield has fallen from above 5% to a recent 3.6%. It started running in 1980, when a series of interest rate increases by the Federal Reserve finally broke the back ofinflation , and it galloped onward for more than three decades. As I noted last week, drug stocks traded for a number of years withdividend yields in excess of 5% to compensate for a lack of share price growth.