While China's unprecedented currency moves have quickly become the main talking point across global markets which otherwise have started off 2017 in an eerily calm fashion, it is the sudden surge in two-way volatility that has emerged a major threat to global market stability.

Case in point, the offshore Yuan fell as much as 1.1% to 6.8623 a dollar in Hong Kong, the most in exactly one year, after a record 2.5% surge over the past two sessions. This took place as a result of conflicting signals, as on one hand China continued to drain liquidity and sent overnight deposit rates into all time high territory, yet on the other the PBOC raised its fixing less than projected, but still the most since 2005, and Goldman Sachs advised its lients that the best time to short the yuan are just after interventions - like the recent one - which flush out bearish positions, or when China concerns were off traders’ radar screens.

China’s central bank raised its daily reference rate by 0.92% to 6.8668 per dollar on Friday the biggest rise since unpegging from the US dollar in 2005, following a 1 percent drop in a gauge of the greenback’s strength overnight. The offshore yuan was trading 0.8 percent weaker at 6.8457 per dollar as of 5:23 p.m. in Hong Kong, paring its weekly gain to 1.9 percent, the most in data going back to 2010. The onshore rate slumped 0.6 percent. Friday’s fixing was weaker than Mizuho Bank Ltd.’s prediction of 6.8447 and Australia & New Zealand Banking Group Ltd.’s estimate of 6.8456.

As we observed on Thursday evening, Yuan short sellers were once again squeezed in Hong Kong this week after interbank borrowing rates soared, and the dollar weakened as Bloomberg News reported that Chinese policy makers were preparing contingency plans to support the exchange rate even as they prepared for trade war with Donald Trump.

The three-month yuan interbank rate in Hong Kong, known as Hibor, surged to a record high, while the overnight rate jumped 23 percentage points to 61 percent, the highest since last January’s cash crunch. Rising interbank rates can make some short positions prohibitively expensive.

The move widened the offshore yuan’s premium over the onshore rate to 1.6%, the most since February last year. While borrowing rates in Hong Kong remained elevated on Friday, a broad recovery in the U.S. currency eased some of the pressure on bears.

Speaking to Bloomberg, Roy Teo, senior currency strategist at ABN Amro Bank NV in Singapore said that “The offshore yuan is sinking because there is some recovery in the dollar, perhaps the unwinding of short-yuan positions has mostly been done, and it’s closing the gap with the onshore currency.” The yuan is likely to weaken this year as capital outflows continue and the U.S. Federal Reserve increases interest rates, Teo said.

As shown in the chart below, in wildly volatile swings, the gave back much of its gains after a week that echoed the short squeeze in January of last year. That abrupt reversal marked the beginning of a nearly 5 percent rally lasting two months.

Chinese policy makers have several reasons to engineer a stronger or stable yuan in the short term. U.S. President-elect Donald Trump has pledged to label the country a currency manipulator on his first day in office, while the exchange rate came close to breaking through the psychologically-important level of 7 per dollar earlier this week. Policy makers also want to avoid a flood of capital outflows as citizens’ annual foreign-exchange quotas reset for the new year.

Meanwhile, Goldman warned that the Yuan will probably drop to 7.3 per dollar by December, emerging-market strategists led by Kamakshya Trivedi in London predicted in a note dated Thursday.

“The squeeze will have a temporary impact,” Luke Spajic, head of emerging Asia portfolio management at Pacific Investment Management Co., said in Hong Kong. “But I don’t think it necessarily changes the challenge, and the challenge is they still have to worry about the $50 billion to $60 billion a month of outflows and what they’re going to do about the value of their currency. And they have to face the fact that the U.S. is probably going to keep hiking rates.”

Benjamin Fuchs, chief investment officer at the $2 billion hedge fund BFAM Partners (Hong Kong), said China’s moves to repeatedly tighten capital controls risk eroding confidence in its currency. The dollar’s advance against the yen and other currencies has also increased competitive pressure on China to let the yuan depreciate, he said.

“We’re starting to see more and more of a negative cycle being created,” Fuchs said. China’s attempts to curb outflows are “just making people want to take money out quicker, and make companies change their behavior.”

The biggest problem, however, is that this volatility is starting to spillover into other currency, and asset markets, and as a result of the Chinese interventions even the dollar is starting to backoff from its recent 13 yearhighs.

Finally, in what may be a mockery of what traders observe every day, moments ago the PBOC said that China will keep the Yuan exchange rate "Basically Stable." It added that it "will continue to improve yuan exchange rate formation mechanism this year" according to a statement after PBOC annual meeting on 2017 work.

Among other PBOC focuses:

To improve policy framework, infrastructure for global yuan: PBOC

To maintain prudent, neutral monetary policy: PBOC

To keep liquidity basically stable: PBOC

Considering that China has failed abysmally at all three so far, markets are increasingly concerned that the worst possible outcome may be inevitable: China losing control over the currency. The global consequences would be severe.