Then and Now, from Kim Zussman
We are now 15 days since the drop of 2/27, and SPY is about three percent below where it was 16 days ago. This is near the 2.9% below 5/11/06, which occurred 15 days after that decline started.
To compare these events I plotted change in SPY closing price for each series such that the declines are superimposed trading day for trading day:
Though the recent decline was much sharper initially, it rebounded more quickly before converging with last summer's drop. Hopefully there is little to conclude from the parallel beyond this.