That’s the message in Banco Santander’s  agreement Wednesday to buy out its minority partner in Santander Mexico, Bank of America , for $2.5 billion.

The deal will hand the U.S. bank a $900 million gain on an investment made seven years ago as a bet on the growth of banking services in Mexico.

And it will give Santander, which currently owns 75% of Santander Mexico, an opportunity to reap the full rewards of the so-called bankarization strategy that aims to sell more services to the nation’s poor.

“This acquisition reinforces Santander’s commitment to Mexico, a country with a very positive outlook for growth, and furthers the geographic diversification of our Group,” Santander Chairman Emilio Botín said in a press statement.

He said the purchase will boost the Mexican bank’s contributions to Santander’s profits.

That’s important because Spanish banks have been under immense pressure, amid worries about Spain’s fiscal straits. The spread of Spanish 10-year bonds to similar German debt has tripled this year, as investors flee the risk of bonds issued by weaker sovereign states. That has pushed up Spain’s costs of funding government spending.

Spanish bank stocks have been hammered as a result. Santander is down 45% this year and Banco Bilbao , the nation’s No. 2 bank, is down 50%. Analysts there said this week that the Spanish banking industry needs to raise $60 billion in new capital to fill holes opened by the housing bust and 20% unemployment.

At the same time, the biggest problems in Spain’s banking system seem to be concentrated in the smaller institutions, which are already having trouble getting funding in the market, Reuters reports.

Early Wednesday, Santander and Banco Bilbao were up modestly.