When Federal Reserve officials meet next week to decide whether to cut interest rates again, they’ll face another question that’s becoming increasingly urgent — how soon they should stop shrinking the bank’s $6.6 trillion portfolio of securities. Money markets have been flashing warnings for several weeks that the process, known as quantitative tightening, may have run its course. Now, Wall Street strategists say, stress signals have gathered such momentum that the Fed may be forced to end QT as soon as t ...