Over the past few years Santander has expanded in emerging economies in search of faster growth than in Europe, where ultra-low interest rates had made banking less profitable.

Spain's biggest bank had set the offer price to Santander Mexico shareholders at 24.52 Mexican pesos ($1.35) for each Series B share in Mexico and the U.S. dollar equivalent of 122.6 pesos for each American Depositary Share (ADS) listed in New York.

That valued the unit at around 8.4 billion euros. The Spanish bank expects to pay the purchase price for Series B Shares and ADSs on Thursday.

The Spanish bank will incorporate a repurchase trust on the date of the cancellation of the B shares, and said holders of outstanding shares will have the right to sell them to the trust for the same amount within a six-month period.

Santander will be able to delist the shares of its unit from the Mexican stock exchange and remove its ADSs from the New York stock exchange

(Reporting by Jesús Aguado; Editing by Inti Landauro and Jan Harvey)