In the last trading session, Wall Street extended its decline for the fourth straight day on renewed fears of an aggressive rate hike by the Fed. Among the top ETFs, (SPY Quick QuoteSPY - Free Report) lost 0.8% and (DIA Quick QuoteDIA - Free Report) shed 0.7%, while (QQQ Quick QuoteQQQ - Free Report) moved 0.6% 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.

(IYH Quick QuoteIYH - Free Report) : Volume 6.51 Times Average

This healthcare ETF was in the spotlight as around 411,000 shares moved hands compared with an average of 70,000 shares a day. We also saw some price movement as IYH lost 0.6% in the last session.

The move was largely the result of investors’ flight to defensive investment amid the market turmoil that could have a big impact on healthcare ETFs like the ones we find in this ETF portfolio. IYH has declined 5.6% over the past month and has a Zacks ETF Rank #1 (Strong Buy) with a High risk outlook.

(PTF Quick QuotePTF - Free Report) : Volume 3.34 Times Average

This technology ETF was under the microscope as nearly 33,000 shares moved hands. This compares with an average trading volume of roughly 10,000 shares and came as PTF shed 0.8% in the last trading session.

The movement can largely be blamed on Fed rate hike fears that took a toll on the tech sector. PTF has plunged 5% in a month’s time and has a Zacks ETF Rank #2 (Buy) with a High risk outlook.