Shares of United Technologies Corp. UTX, +11.88% shot up 12.2% in afternoon trading, just one day after recording the biggest-ever one-day percentage gain of 15.8%. That puts the stock on track to post back-to-back double-digit percentage gains for the first time in its history, according to available FactSet data doing back to May 1975. The historic 2-day rally comes after the stock closed at a 7 1/2-year low of $74.95 on Monday. On Wednesday, the aerospace and building systems company’s stock was adding about 72 points to the Dow Jones Industrial Average’s DJIA, +5.17% price, which was up 1,161 points, a day after rocketing 2,113 points.