In the last trading session, U.S. stocks registered the biggest one-day loss since Jun 23’s Brexit referendum owing to increasing chances of a rate hike. Among the top ETFs, investors saw (SPY – ETF report) plunge about 2.4%, (DIA – ETF report) decline around 2.1% and (QQQ – ETF report) advance about 2.5% on the day.

Two more specialized ETFs are worth noting in particular though as both saw trading volume that was far outside of normal. In fact, in the most recent trading session, both these funds experienced volume levels that were more than double their average. This could make these ETFs the ones to watch out for in the days ahead to see if this trend of extra interest continues:

(VXX – ETF report) : Volume 3.4 times average

This volatility ETF was under the microscope on Friday as nearly 77.8 million shares moved hands. This compares to an average trading volume of 24.16 million shares and came as VXX surged about 16.1% in the session.

Surge in volatility level during Friday’s session played a major role in boosting the ETF. Increase in rate hike fears following comments from some of the Fed officials led the fear-gauge CBOE Volatility Index (VIX) to jump at the highest pace since Jun 24. In the last one-month period, VXX increased nearly 3.8%.

(DJP – ETF report) : Volume 3.99 times average

This commodity ETF was in focus on Friday as roughly 1.37 million shares moved hands compared with an average of roughly 357,870 shares. DJP lost about 1.4% on the day.

A strengthening U.S. dollar against major currencies had a negative impact on commodity prices including oil, which in turn led the ETF down on Friday. Rise in rate hike speculations led the U.S. to spike in the last trading session. However, in the last one-month period, DJP was up 1.1%.