Goldman Sachs has been trying to clean up a mess inside its publicly traded private-lending company for more than three years. Investors are still unimpressed.The banks business-development company, Goldman Sachs BDC, is primarily a lender to middle-market corporations. Like all BDCs, it raises funds by selling shares, or taking on its own debt, and lends it out in bespoke private-credit deals, with the income paid out in dividends.