European banks posted significant gains Monday amid a surge in regional benchmarks as investors reacted to Sunday's presidential elections in France and the prospect of a second round win for centrist candidate Emmanuel Macron.

The region's biggest banks posted some of their biggest gains in a year in early trading as the euro hovered at a multi-week high against the U.S. dollar and government bonds -- outside of Germany -- rallied hard in the wake of Macron's win and his early lead in second round polls over far-right rival Marine Le Pen. The region-wide Stoxx 600 Europe Banks index gained 4.5% to touch a 52-week high of 183.46. 

France's BNP Paribas SA  (BNPQY) , the country's biggest bank, gained more than 8.6% to trade at €67.32 each, lifting domestic lenders Societe Generale SA (SCGLY) (9.65%) and Credit Agricole SA (CRARY) (9.7%) to significant early gains. Commerzbank AG  (CRZBY) , Germany's second-biggest bank, was marked 9.8% higher by mid-day trading while Deutsche Bank AG (DB) - Get Deutsche Bank AG Report surged 8.56% to a one-month high of €16.77 each. Banco Santander (SAN) - Get Banco Santander S.A. Sponsored ADR Report, Spain's biggest lender, was marked 5.3% higher at €5.97.

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Macron, a former investment banker who served as Economy Minister for the current President, Francois Hollande, secured 23.75% of the vote, which was spilt among 11 candidates, based on final official figures from France's Interior Ministry.

Le Pen, the daughter of Jean-Marie Le Pen, who run unsuccessfully for President in 1995, finishing a distant second to Jacques Chirac, won 21.53% of the vote and will meet Macron in a run-off on May 7.

However, given the breadth of support for establishments candidates such as Francois Filion and Benoit Hamon -- who immediately endorsed Macron -- it is unlikely that Le Pen can win enough support in the head-to-head competition to secure her place at the Elysee Palace.