Stocks with the weakest balance sheets have climbed more than 8 percent in 2014 and 94 percent since the end of 2011, generating almost twice the gain in the Standard & Poor’s 500 Index (SPX) over that period, according to data compiled by Bloomberg and Goldman Sachs Group Inc. Shares in the category this year are beating those that most investors consider the bull market’s leaders, such as small caps and biotechnology, which tumbled in March. Helped by rising bond issuance and falling defaults, stocks from Tenet Healthcare Corp. to Frontier Communications Corp.