Trading volume is number of shares traded, not number of trades. Re-reading, it was actually ~600% greater volume. "The difference reached a peak at 9:58 a.m.,

Trading volume is number of shares traded, not number of trades. Re-reading, it was actually ~600% greater volume. "The difference reached a peak at 9:58 a.m., when the volume was six times greater." That's pretty noticable!