Local banking groups are turning to non-banking businesses through takeovers in a bid to diversify their portfolios, cornered by shrinking profit margins and a saturated market, data showed Tuesday. NongHyup Financial Group finalized a deal to buy the three units of Woori Finance Holdings Co., including Woori Investment & Securities Co. The group's market share is expected to top its rivals in the brokerage sector once Woori Investment & Securities merges with its securities unit, NH Investment & Securities Co