The real reason behind the EM rout

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Forget fears of a U.S. interest rate hike, the current emerging market selloff has a new narrative, according to one analyst.

"[Tuesday's market selloff] in Asia has a lot more to do with broader global disinflationary fears," than with the Federal Open Market Committee (FOMC), Adarsh Sinha, head of Asia Pacific G-10 FX strategy at Bank of America Merrill Lynch, told CNBC.

"Nowhere is that more evident than inflation break evens across the developed markets," he said, referring to soft growth in European consumer prices and Japanese inflation hitting a one-year low in October.

MSCI's Emerging Markets Index fell to new 10-month low on Tuesday, with Thailand's benchmark index once again leading declines in Asia. The SET index traded at six-month lows for the second straight session, down 3 percent by the afternoon after sinking as much as 9 percent on Monday.

Read MoreDespite risks, Thailand may consider rate cut

Other experts said Sinha's argument wasn't groundless with lower oil prices driving global disinflation. Crude prices fell to new five-year lows on Tuesday, with Brent crude down 45 percent year-to-date.

"It looks like a valuation trade. The biggest reason for the EM rout is volatility spiking higher, triggered by oil and now ballooned into a broader equity market selloff," said Vishnu Varathan, senior economist at Mizuho Bank.

"It's difficult to isolate and eliminate factors, there are no convenient attributions. You have EM carry trades coming off as long bets are unwound, while year-end dollar demand is also playing a role," he added.

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Not just exporters

This week's selloff also spread to energy importing nations, like Indonesia and India, which many view as a catch up to the selling seen in exporter peers.

Indonesian stocks fell 2 percent to a one-month low on Tuesday, while the rupiah hit a fresh 16-year low against the greenback for the second straight day. Meanwhile, India's rupee tumbled to a 13-month low and the Nifty index lost 1 percent.

"Nobody's thinking anymore about which Asian country benefits from lower oil prices and which don't. When the market prices in disinflationary fears, that's an environment which historically tends to be really bad for Asian currencies, particularly those that are high-yielders and have current account deficits," Sinha said.

Read MoreWhy Russia's monster rate hike spells trouble ahead

Some believe the steep market declines in importers could even be a buying opportunity.

"If you look at major importers, like India or China, you have to start thinking this will be an opportunity for a longer-term investment. We do need to get through the Fed comments on Wednesday in order to have a clearer view on what emerging markets will look like in the next few weeks, but I think if someone has a year-long horizon, this may prove to be a very good buying opportunity for energy importing countries," said David Riedel, president and founder of Riedel Research.

All eyes on Fed

The selloff comes a day before the outcome of the Federal Reserve's monetary policy meeting on Wednesday. Traders are debating whether the bank will drop the phrase that benchmark rates will remain low "for a considerable period of time."

"If they did remove that phrase, I think you're going to see all those usual suspects that have gotten hurt during taper tantrums in the past decline again, like Indonesia, Malaysia, South Africa, Turkey," Riedel added.

He dismissed possibilities that bad news could be priced in this time around.

Read MoreThe silver lining to cheap oil in the Middle East

"I'm not big believer that emerging markets price in a lot of things ahead of the news. Look at the Brazilian elections and sanctions on Russia… Markets do tend to wait until the news is confirmed before reacting. If you think rates will rise in the U.S. earlier rather than later, I would wait until that's digested by the market because we could see another leg down," he said.

Weak Chinese data on Tuesday also played a role, with the latest HSBC manufacturing purchasing manager's index (PMI) print dropping into negative territory for the first time since May.

"In a week where the Federal Reserve is expected to take a hawkish shift in tone, the last thing emerging markets need is some unsettling economic data. While some would have hoped to see disappointing China data result in growing calls for stimulus, this has not been the case today and we've actually seen investor concerns heighten. China activity generally ramps up heading into the back end of the year but it doesn't seem like this will be the case this time," Stan Shamu, market strategist at IG, said in a note.