Japanese financial firm Orix Corp. said Tuesday it will buy Dutch asset manager Robeco for about 1.94 billion euros ($2.58 billion) in what would its biggest acquisition. Under the deal, Orix will buy a 90.1 percent stake in Robeco from Dutch lender Rabobank, which will keep the remaining 9.99 percent stake. The deal would help Orix strengthen its presence in the global asset management business, giving it an opportunity to offer Robeco's financial products to Japanese customers, it said.