In the Market: The mysterious one-day drop in a repo rate

Something odd just happened in U.S. short-term funding markets: a benchmark interest rate suddenly fell precipitously on March 19 before bouncing back up the next day. The drop, which has garnered little attention outside Wall Street trading desks, happened in a corner of the repurchase agreement market, or repo, where firms borrow funds from investors against Treasuries. That day a key repo interest rate, called the Treasury GCF Repo Index, fell to 5.142%, a significant drop from its previous day's print of 5.334%.