On October 15, 2014, there was a "flash crash" in US Treasuries. The yield on the US 1o-year note fell 34 basis points — or 0.34% — from 2.2% to as low as 1.86% in a matter of just minutes. And a report from Bloomberg's Matt Boesler on Monday shows that regulators still aren't sure what to make of this event or what it could mean during future bouts of market volatility.