Banco Santander (STD) scooped up Bank of America's (BAC) 24.9% stake in Santander Mexico for $2.5 billion in cash, giving the Spanish bank virtually total control of the Mexican unit and less exposure to its own hurting domestic economy.

Santander Mexico had been part of Banco Santander since 1997 and the transaction will boost Mexico's contribution to the bank's profits by two percentage points to 7%.

"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," Emilio Botin, chairman of Banco Santander, said in a statement.

The sale comes at a profit for Bank of America, which acquired a 24.9% stake in the unit from Banco Santander in 2003 for $1.6 billion. The latest deal places a $10 billion value on Santander Mexico, a 56% rise in valuation. By reacquiring the stake from BofA, Banco Santander owns 99.9% of the company.

The move is targeted at both building Banco Santander's exposure to fast-growing Mexico and limiting its risk to Spain's economy, which has been damaged by the European sovereign debt crisis.

In fact, Banco Santander's own stock has lost nearly half of its value so far this year amid fears Spain will become a much larger version of Greece, the epicenter of the debt debacle. Shares of Banco Santander rose 1.56% to $9.09 in the wake of the deal for the Mexican unit.

Banco Santander is already the third-largest financial group in Mexico, with a 13% market share in loans and 14.8% in deposits.

BofA's stock declined modestly despite a minor rally in the financial sector, sinking 0.65% to $15.23.