In the last trading session, U.S. stocks were mixed. Among the top ETFs, investors saw SPY and QQQ gaining about 0.1% and 0.7%, respectively, while DIA move lower by 0.1% on the day.

Two more specialized ETFs are also worth watching 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 of the last trading session. This could make these ETFs ones to watch out for in the days ahead to see if this trend of extra-interest continues.

PGF: Volume 4.06 times average

This financial preferred ETF was under the microscope yesterday as about 3.25 million shares changed hands. This compares to the average trading volume of around 800,000 shares and came as PGF gained about 0.7% in the session.

The big move was probably the result of investors’ demand for higher yield. The fund has added about 4.7% in the past one month.

DBC: Volume 2.87 times average

This broad commodity ETF was in the spotlight yesterday as nearly 6.45 million shares moved hands compared with an average of roughly 2.25 million shares a day. The fund gained about 0.3% in the last trading session.

The movement can largely be credit to the rise in crude prices amid speculation that the United States may pose strict sanctions against Venezuela’s energy sector. Since the fund is heavy on crude, it saw solid trading volume. For the month, DBC is down about 5.2%.

Want key ETF info delivered straight to your inbox?

Zacks’ free Fund Newsletter will brief you on top news and analysis, as well as top-performing ETFs, each week. Get it free >

Zacks Names "Single Best Pick to Double"

From thousands of stocks, 5 Zacks experts each have chosen their favorite to skyrocket +100% or more in months to come. From those 5, Director of Research Sheraz Mian hand-picks one to have the most explosive upside of all.

It’s a little-known chemical company that’s up 65% over last year, yet still dirt cheap. With unrelenting demand, soaring 2022 earnings estimates, and $1.5 billion for repurchasing shares, retail investors could jump in at any time.

This company could rival or surpass other recent Zacks’ Stocks Set to Double like Boston Beer Company which shot up +143.0% in little more than 9 months and NVIDIA which boomed +175.9% in one year.

Free: See Our Top Stock and 4 Runners Up >>