M1 has become basically a meaningless category. The Fed blog post says that their April 24 change to Regulation D allows banks to remove the 6 tx/month limit on savings and money market accounts, which classifies them as M1. The growth in M1 since April has largely been banks changing their policies and their reporting strategies.

Sure enough, the rapid growth in M1 starts on April 24, and M1 is now about $1B less than M2 (roughly $18B vs. $19B). We should be looking at M2, which has grown by about 25% ($15-19T): still a big story, but nowhere near as dramatic as this graph.