The NYSE will implement an SEC experiment.

The Securities and Exchange Commission proposed an experiment in hopes of dampening the wild price fluctuations that can whipsaw market investors in the final minutes of “triple-witching” Fridays. The agreement calls for the Big Board to publicly disclose major imbalances in market-closing orders for key stocks on days when stock options, stock index options and futures contracts expire simultaneously. There are four such triple-witching days each year, on the third Fridays of March, June, September and December. The experiment will begin on the next one, Sept. 19.