LONDON — Alfredo Saenz resigned Monday as chief executive of Banco Santander, a move that ends a period of uncertainty over the bank’s leadership as Saenz faced a possible ban from banking after a criminal conviction.
Saenz’s decision also comes less than a week after Spain’s largest bank reported that first-quarter net profit fell 26 percent.
He will be succeeded by Javier Marin, 47, who has worked for Santander for two decades — mainly in its private banking arm — and is currently head of its insurance, asset management, and private banking operations.
Saenz is departing with a retirement compensation package worth about $115 million. He has also remained one of Spain’s best-paid chief executives, earning $10.7 million last year, despite taking a pay cut of 29 percent.
Banco Santander owns Sovereign Bank, one of the largest regional banks in New England.
Saenz, 70, joined Santander in 1994 after the bank acquired a local rival, Banesto. Since then, he helped Santander’s chairman, Emilio Botin, 78, transform the firm from a regional lender to an international giant with operations from the United States to Poland.
Yet Saenz has also faced a series of legal problems, including his conviction in 2009 for making false accusations in the early 1990s in a case involving Banesto. He was later pardoned by Spain’s departing Socialist government in 2011, though the country’s Supreme Court partly overturned that decision this year.
Santander has also been hurt by persistent problems in Europe, as well as by increasing headwinds in emerging markets like Brazil. Last year, Santander set aside provisions totaling $25 billion to cover a rise in delinquent mortgages in Spain’s struggling economy and an increase in other troubled loans across its businesses.
In Latin America, where Santander earns more than half of its net income, a slowdown in economic growth and an increase in troubled loans is starting to cause problems.
First-quarter earnings for the region, for example, fell 18 percent, to $1.3 billion, despite an increase in local lending and customer deposits. The firm’s profit from Continental Europe in that period plunged 27 percent, to $401 million.
The decision by Saenz to step down comes after several months of uncertainty. Spain’s Supreme Court ruled in February that the country’s previous government had gone too far in its pardon of Saenz, which had raised concerns over his tenure.
As part of its decision, the court reinstated Saenz’s criminal record, casting doubt over whether he could continue as a senior executive at Santander.
The current Spanish government passed a law this month that allows bankers with criminal convictions to continue working in the country’s financial industry, but that still left Saenz exposed to a final ruling by the Bank of Spain over his eligibility as a banker. Analysts said the decision for Saenz to step down was an attempt to ease the uncertainty before any decision by the Bank of Spain in the coming month.
Even though Santander described Saenz’s decision as voluntary, ‘‘maybe it was too risky for Santander to be exposed to an inconvenient decision by the Bank of Spain in the next three or four weeks,’’ said Robert Tornabell, professor at Esade business school in Barcelona.
Shares in Santander closed up 2.6 percent Monday.
Saenz’s successor, Marin, is credited with striking several important insurance alliances for Santander, notably with Zurich, the Swiss insurer, covering its Latin American operations, and with Aegon last year.
Still, Marin’s appointment came as a surprise, given his low profile until now among Santander’s top management.
“He would be relatively unknown to the wider investment community, so I guess it may take him a bit of time to establish a rapport with investors,’’ said Daragh Quinn, banking analyst at Nomura in London.
The appointment also thrusts Marin’s name on the list of possible candidates to succeed eventually Botin. That list also includes Botin’s daughter, Ana Patricia Botin, who is in charge of the bank’s British operations.
Tornabell, the banking professor, suggested that Botin was maneuvering like ‘‘in a chess game,’’ rejuvenating his leadership amid an earnings decline before probably still appointing his daughter to replace him.
Still, Tornabell suggested that some institutional investors had become worried about Botin running his bank as ‘‘a monarchy dynasty,’’ despite owning only about 2 percent of its equity.