In the last trading session, U.S. stocks showed signs of weakness. Top ETFs, SPY declined 0.6%, DIA moved down 0.2% and QQQ fell around 0.7% on the day.Two more specialized ETFs are worth taking a note of in particular though as both saw trading volume that were more than double their average for the most recent trading session. This could make these ETFs worth a watch in the days ahead if this trend of extra-interest continues:SCHP: Volume 4.8 times averageThis U.S. TIPS ETF, which tracks the performance of U.S. Treasury Inflation Protected Securities (TIPS), was in focus on Friday as roughly 2.8 million shares moved hands on the day compared to an average of roughly 619,000. We also saw some share price movement as it lost around 0.1%.The movement can largely be blamed on weakening bets on aggressive rate cuts by the Fed, making the TIPS ETFs unattractive. For the month, SCHP has lost 0.2%.SLV: Volume 4 times averageThis silver bullion ETF is being closely watched as nearly 41.9 million shares moved hands on Friday. This compares to an average trading day of around 11 million shares and it came as SLV lost around 0.8% on the session.The big move on Friday was probably the result of a gain in the U.S. dollar, which in turn weighed on silver bullion prices. SLV has gained around 4.9% in the past month. The fund has a Zacks ETF Rank #3 (Hold).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 SPDR Dow Jones Industrial Average ETF (DIA): ETF Research Reports iShares Silver Trust (SLV): ETF Research Reports Schwab U.S. TIPS ETF (SCHP): ETF Research Reports Invesco QQQ (QQQ): ETF Research Reports SPDR S&P 500 ETF (SPY): ETF Research Reports To read this article on Zacks.com click here. Zacks Investment Research 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