Walmart, the nation’s largest retailer, is launching its own mobile payment service.

It was announced late last night that Walmart Pay would join the growing parade of branded mobile payment platforms: Chase Pay, Android Pay, Samsung Pay, and Apple Pay. Bentonville, Ark.-based Walmart had previously been known in the mobile payments space for not turning on NFC at its registers, thereby blocking Android Pay and Apple Pay, and for its support of MCX, the merchant-driven mobile payments platform.

Walmart Pay will not be ready for consumers in time for holiday shopping. Its launch is slated for mid-2016.

The emergence of Walmart Pay casts the Walmart-MCX alliance in doubt, though Daniel Eckert, Walmart’s U.S. head of services, told The Wall Street Journal that Walmart remains committed to MCX and the CurrentC app. In the future, Walmart Pay could work in concert with MCX and even Apple Pay through Walmart’s app.

But Brian Roemmele noted in Forbes that this could be a mortal blow to MCX, and that CurrentC may not launch at all. Further, megabrands such as Target and Best Buy may defect entirely to Android Pay and Apple Pay.

Walmart’s app has some 22 million users, according to the company, and 75% of its users own smartphones. Walmart Pay uses cards stored in Walmart.com and communicates with points-of-sale via QR code — just like MCX and CurrentC. The app must be opened to use, but it offers receipts, an imp

The timing of the announcement struck some observers as strange, and led Cherian Abraham, payments, commerce and fraud analyst at Experian, to wonder if it might have been a pilot test unintentionally made public.

Two things on Walmart Pay 1) Timing is really weird. No one does a December launch. Ever. 2) Looks more like a https://t.co/E7QxX74ZpT test.

— Cherian Abraham (@cherian_abraham) December 10, 2015

Certainly, MCX hopes it was all big mistake.

UPDATE: Tom Noyes, CEO of Commerce Signals, says the timing of this announcement is great and that the biggest loser here is… Chase Pay.