Blackbaud (BLKB -15.16%) stock is sinking Tuesday. The software specialist's share price was down 12.6% as of 3 p.m. ET, according to data from S&P Global Market Intelligence.Blackbaud published its fourth-quarter results after the market closed yesterday. While the company's non-GAAP (adjusted) earnings per share of $1.14 beat the average analyst estimate's call for per-share earnings of $1.05, revenue for the period missed Wall Street's target. The company posted sales of roughly $295 million, while the a ...