In the last trading session, U.S. stocks saw rough trading sparked by a slew of weaker-than-expected economic data out of China and Europe that sparked fresh worries over the world’s second-biggest economy and prospects of global growth. Among the top ETFs, investors saw (SPY - Free Report) lose 1.8%, (DIA - Free Report) shed 2%, and (QQQ - Free Report) move lower by 2.4% 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:

(VGSH - Free Report) : Volume 5.72 Times Average

This short-term Treasury ETF was under the microscope as 4.8 million shares moved hands. This compares with an average trading day of roughly 913,000 shares and came as VGSH added 0.05% in the trading session.

The movement can largely be blamed on protection from rising rates as short-duration bond ETFs are less vulnerable and act as a better hedge to rising rates. VGSH has added 0.4% in a month’s time and carries a Zacks ETF Rank #4 (Sell) with a Medium risk outlook.

(ACWX - Free Report) : Volume 3.11 Times Average

This world ETF was in the spotlight as around 6.4 million shares moved hands compared with an average of 2.1 million shares a day. We also saw some price movement as ACWX lost 1.3% in the last session.

The big move was largely the result of weak economic indicators that can have a big impact on global stocks like what we find in this ETF portfolio. ACWX has lost 3.7% over the past month and carries a Zacks ETF Rank #3 (Hold) with a Medium risk outlook.