The last trading session has been a mixed one for U.S. stocks. Among the top ETFs, (SPY Quick QuoteSPY - Free Report)  lost about 0.2%, (DIA Quick QuoteDIA - Free Report)  moved 0.3% lower but (QQQ Quick QuoteQQQ - Free Report)  gained 0.1% on the day. Subdued retail sales probably weighed on the market.

Two other specialized ETFs are also worth watching as both saw higher-than-normal trading volume. In fact, both funds experienced volume levels that were more than double their average for most part of the last trading session. This could make these ETFs the ones to watch out for in the days ahead to see if the trend continues.

FCG: Volume 3.57 times average

This natural gas ETF was closely watched yesterday as about 1.21 million shares changed hands. This compares to the average trading volume of around 339.90 shares and FCG gained about 0.5% in the session.

Investors should note that gasoline prices are on the rise now. This was because “U.S. Gulf of Mexico refineries continued to be disproportionately affected by crude oil supplies from Venezuela” amid U.S. sanctions. The fund has lost about 3.7% in the past month.

KBE: Volume 2.76 times average

This bank ETF was in the spotlight yesterday as nearly 9.8 million shares moved hands compared with an average of roughly 3.55 million shares a day. The fund lost about 1% in the last trading session. Decline in benchmark treasury yields amid disappointing retail sales data hurt bank stocks and led to the elevated volume. For the month, KBE is up about 8.4%.

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 >