UPDATE 2-Brazil's Nubank posts sixfold profit jump on client base growth

(Adds specific customer numbers in paragraph 7 and comments from CFO in final paragraph)

By Patricia Vilas Boas

SAO PAULO, Feb 22 (Reuters) - Brazilian financial technology firm Nubank on Thursday posted a more-than-sixfold increase in net profit in the fourth quarter, as it added nearly 5 million new customers to its ranks.

Nubank's net profit jumped up to $360.9 million, though it missed the $410.7 million estimate of analysts compiled by LSEG.

Its return on equity (ROE) - a measure of financial performance - hit 23% in the quarter.

Revenues at the firm were up to a record $2.4 billion, a 57% boost on a currency-neutral basis from the year-ago quarter, Nubank said, topping estimates.

Average monthly revenue per active customer grew 23% on a currency-neutral basis in the quarter as well.

The firm's credit portfolio also improved slightly, with loans overdue by 15 to 90 days decreasing to 4.1%. Loans overdue by more than 90 days remained stable at 6.1%, Nubank said, in line with expectations.

Nubank hit nearly 94 million clients in the quarter, it said, and is aiming to top 100 million this year. It reached 87.8 million in Brazil at the end of the quarter, while in Mexico there were 5.2 million customers and in Colombia more than 800,000.

Chief Financial Officer Guilherme Lago said in a call with analysts that the company's priorities now include working to "win the game" in Mexico, where Nubank is rapidly gaining market share.

CEO David Velez said in a statement Nubank was also looking to tap into the "not-yet-fully-explored opportunity" in both unsecured and secured loans, as well as growing its market share in Brazil's high-income segment.

(Reporting by Patricia Vilas Boas and Kylie Madry; Editing by Steven Grattan and Aurora Ellis)