The Australian dollarhas been having a rough ride, and this strategist says there's more to come.

Willie Williams, global macro institutional sales director at Societe Generale, has been watching the selloff in emerging market currencies, and he thinks it will have a ripple effect that will hurt other currencies.

Earlier in the year, Williams says, some sovereign wealth funds "were buyers of the euro as they looked to diversify their reserves" and keep their own currencies from rising too sharply. But with volatility on the rise - the VIX is over 40 now, compared to 20 three months ago - those emerging market currencies are hurting and the sovereign wealth funds have changed course.

"This week we saw Korea, Russia, Poland and Brazil all come in to strengthen their currencies," Williams says - which means some big euro buyers are out of the picture.

That's obviously a negative for the euro, and Williams does like selling the euro. But he views the Australian dollar as a better currency to short. 

"At some point in time, you will see some sovereign wealth funds come back into the market," he told CNBC's Scott Wapner. That means the Aussie, lacking a similar lifeline, is a better sell.

Williams recommends selling the Aussie against the dollar at 0.9850, with a stop of 1.0050 and a target of 0.9300.

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