Spain’s Banco Santander SA (MCE:SAN), the euro zone’s largest bank by market value, wrote down a stunning $26 billion in assets, primarily because of plunging Spanish real estate values and delinquent loans in the recession-wracked economy.

The Madrid-based bank also said on Thursday that its net profit for 2012 dropped 59 percent as its European business declined and revenue from operations in the U.K., Mexico and Brazil was weak.

“Spain by itself should be enough to make 2012 a turning point for earnings because there were a lot of one-off costs for real estate,” Carlos Joaquim Peixoto, an analyst at Banco BPI SA in Portugal, told Bloomberg News.

“The performance of other regions, especially Brazil, still represents a significant challenge.”