In the last trading session, U.S. stocks have been on a rocky ride given the new tariff threat that has escalated the trade spat between the United States and China. Among the top ETFs, investors saw SPY shed 1.6%, DIA lose 1.7%, and QQQ move 2% lower 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.

(PTH Quick QuotePTH - Free Report) : Volume 9.65 Times Average

This healthcare ETF was under the microscope as 175,000 shares moved hands. This compares with average trading volume of roughly 18,000 shares and came as PTH lost 2% in the trading session.

The big move was largely the result of volatility, leading to investors’ defensive tilt that can have a big impact on healthcare stocks like what we find in this ETF portfolio. PTH has lost 1.4% over the past month and carries a Zacks ETF Rank #3 (Hold) with a High risk outlook.

(IVOG Quick QuoteIVOG - Free Report) : Volume 5.10 Times Average

This mid-cap ETF was in the spotlight as around 48,000 shares moved hands compared with an average 10,000 shares a day. We also saw some price movement as IVOG lost 2% in the last session.

The movement can largely be blamed on investors’ caution that compelled them to look for both growth and stability in their portfolio simultaneously. IVOG has shed 0.2% in a month’s time and has a Zacks ETF Rank #2 (Buy) with a Medium risk outlook.

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 >>