An underperformance of MXN is expected, particularly on Thursday, since no change is expected in the fondeo rate, compared with market consensus for a 25bp increase.

The path implied in the TIIE curve for the overnight rate is incompatible with the current macroeconomic setting. Furthermore, neither financial stability concerns nor FX inflation pass-through would warrant an increase in short-term rates. 

"What made us change our mind on the first increase was the FX commission announcement. We were expecting a relaxation in the intervention parameters after the Fed, something that had happened before. We read into that that the commission is willing to tolerate moderate but additional MXN weakness in the months to come", notes Barclays.