Call it the shortest central bank intervention failure in recent history.

Earlier today we reported that just as the tanking Brazilian Real tumbled below 3.80, the Brazilian Central Bank announced another $1.5BN in intervention via swaps about an hour before noon; At that point the USDBRL tested 3.80 into the surprise announcement and tumbled towards 3.76. The central bank first placed 800MM around 11:40EDT with USDBRL testing support, and then placed another 300mn of the 700mn balance and USDBRL, but by then the BRL had resumed sliding toward 3.7850.

The problem, as we noted earlier, is what would happen if despite the 1+ billion intervention, the selloff continued. We got the answer a little after 3pm, when the Brazilian intervention was fully absorbed by the market, and the USDBRL spiked as high as 3.8151, well above the BCB's intervention zone. And now that intervention has failed, the currency predictably closed at the lows, with 2 of Wall Street's largest desks predicting that with the central bank defense having failed, the most likely next stop for the USDBRL is 4.00

The concern, as regular readers will recall, is that if the selloff accelerates beyond 4.00, it could provide the green light for a broader EM crisis because as Bank of America wrote one month ago, "EM FX never lies and a plunge in Brazilian real toward 4 versus US dollar is likely to cause deleveraging and contagion across credit portfolios."

But even without a broader contagion, the question is what happens to Brazil next: the Real has tumbled to early 2016 levels, when Dilma Rouseff was still president, and has now lagged all EM currencies except the imploding Turkish Lira and Argentina Peso.

How long before Brazil become the next locus of EM capital outflows, sending the local market plunging, and spreading to the rest of the EM space?