In the last trading session, the U.S. stocks saw rocky trading as Apple (AAPL Quick QuoteAAPL - Free Report) slipped into bear territory and oil price extended its worst rout. Notably, Dow Jones Industrial Average logged its longest losing streak in three months. Among the top ETFs, investors saw (SPY Quick QuoteSPY - Free Report) lost 0.7%, (DIA Quick QuoteDIA - Free Report) shed 0.8% and QQQ move lower by 0.8% on the day.

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

(UNG Quick QuoteUNG - Free Report) : Volume 13.32 Times Average

This natural gas ETF was in the spotlight yesterday as more than 43.1 million shares moved hands compared with an average of 3.9 million shares a day. We also saw some price movement as UNG surged 18.9% in the last session.

The movement can largely be blamed on a surge natural gas price. Cold weather increases fuel demand for heating purpose, thereby leading to higher natural gas consumption. UNG has soared 50.9% in a month’s time.

(PXE Quick QuotePXE - Free Report) : Volume 6.67 Times Average

This energy ETF was under the microscope yesterday as 227,000 shares moved hands. This compares with an average trading day of roughly 37,000 shares and came as PXE was flat in the trading session.

The big move was largely the result of falling crude prices that can have a big impact on stocks like what we find in this ETF portfolio. PXE has lost 15.5% over the past month and has a Zacks ETF Rank #3 (Hold) with a High risk outlook.

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