Risk-off sentiment into the Fed's interest rate hike made a sharp reversal afterward, leading to lots of strength during a historically weak period. Nigam Arora analyzes money flows on Wall Street's surface through the Mag 7 before taking a look under the surface into the rest of the S&P 500 (SPX) and Nasdaq-100 (NDX). However, he warns that the strength is concentrated as market breadth wanes. Nigam points to Micron (MU) earnings as the next key test for the tech sector.