In the last trading session, Wall Street was downbeat. Among the top ETFs, SPY lost 0.2%, DIA retreated about 0.1% while QQQ moved 0.1% higher 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.WIP: Volume 2.46 Times AverageThis international TIPS ETF was under the microscope as about 148,569 on shares moved hands. This compares with an average trading volume of roughly 60,300 shares and came as WIP lost more than 2% in the last trading session. WIP is down 7% in a month’s time.REM: Volume 3.26 Times AverageThis mortgage real estate ETF was in the spotlight as around 3.07 million shares moved hands compared with an average of 1.09 million shares a day. We also saw some price movement as REM lost 4.7% in the last session. REM has slumped 21.3% over the past month. 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 >>Want the latest recommendations from Zacks Investment Research? Today, you can download 7 Best Stocks for the Next 30 Days. Click to get this free report Invesco QQQ (QQQ): ETF Research Reports SPDR S&P 500 ETF (SPY): ETF Research Reports SPDR Dow Jones Industrial Average ETF (DIA): ETF Research Reports iShares Mortgage Real Estate ETF (REM): ETF Research Reports SPDR FTSE International Government InflationProtectd Bond ETF (WIP): ETF Research Reports To read this article on Zacks.com click here. Zacks Investment Research