ASX plunges 1.7%
Australia's S&P ASX 200 index was one of the biggest losers in the region on Wednesday, with all of its 10 main sectors languishing in the red.
"The market has been steamrolled today. The combination of the Australian dollar breaking 80 U.S. cents, lower iron ore futures and [speculation that] the Reserve Bank of Australia could have ended its easing cycle is having a clear effect," Chris Weston, IG's market analyst, wrote in a note.
Banks were among the hardest-hit; Westpac, National Australia Bank and Commonwealth Bank of Australia closed down more than 2 percent each.
Mining and energy producers also contributed significant downward pressure on the resource-heavy bourse; Fortescue Metals lost 7.4 percent, while Oil Search and Woodside Petroleum receded 2.2 and 1.1 percent, respectively.
Gold-related counters, which were up earlier in the session on the back of firmer gold prices, also succumbed to the selloff; Evolution Mining and Newcrest Mining gave up gains to finish 0.5 and 0.2 percent lower.
On the corporate news front, Wesfarmers, which released its quarterly statement on production, development and exploration, slipped 0.4 percent. IAG tanked over 4 percent after downgrading full-year insurance margin guidance.
Read MoreIron ore rally: Mere dead cat bounce?
SET drops 0.6%
Bangkok's SET index finished at its lowest level since April 1 even as the Bank of Thailand surprised markets with a 25-basis-point cut, bringing its benchmark interest rate down to 1.5 percent.
This is the central bank's second consecutive move to lower interest rates in a bid to prop up a sluggish economy. Data released on Tuesday showed Thai exports fell for a third month in March, hinting that Southeast Asia's second-biggest economy could see a further slowdown in the first three months of the year as a key engine of growth fails to fire up.
Meanwhile, Japanese markets are closed for the Showa Day holiday.