MADRID--Banco Santander SA (SAN.MC) Wednesday said it will price the shares of its Mexican unit at 31.25 Mexican pesos, or $2.437, valuing the entire unit to be floated in Mexico City and New York at approximately 12.8 billion euros ($16.6 billion).

Santander, Spain's largest bank by market value and second-largest firm after retailer Inditex SA (ITX.MC), will sell around 25% of Grupo Financiero Santander Mexico SAB de CV (SANMEX.MX). The bank said 19% of the initial public offering was sold in Mexico, with the rest in the U.S. and other countries.

Santander has marketed the Mexican unit as an opportunity for investors to tap a growing economy with a young population and a relatively low level of banking services. Mexico's gross domestic product is expected to expand by nearly 4% this year, while credit is growing at an annual clip of about 15%

Trading begins Wednesday, and shares on the New York Stock Exchange will be listed under the ticker BSMX.

Write to David Roman at david.roman@dowjones.com Twitter: @dromanber

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