* Q4 profit 3.01 bln pesos
* Loan book up 15 percent to 401.4 billion pesos
MEXICO CITY, Jan 17 (Reuters) - Mexico's fourth-largest bank, Grupo Financiero Banorte, on Thursday posted a 20 percent rise in fourth-quarter profit, helped by lower costs and an increase in funds under management.
Banorte, which last year combined its pension fund with the one run by Mexico's social security institute (IMSS), has expanded as its larger, foreign-owned rivals have had to sell assets to raise capital.
Earlier this month, Banorte and IMSS closed a deal to buy Spanish bank BBVA's Mexican pension fund for $1.735 billion, creating Mexico's largest pension fund with 522 billion pesos ($41.5 billion) under management.
The bank said in a statement that quarterly profit climbed to 3.01 billion pesos ($234 million) in the year-earlier quarter. Comparative figures for the fourth-quarter of 2011 were not immediately available.
Banorte's loan book grew 15 percent to 401.4 billion pesos in the October-December period, compared with the same quarter a year earlier. That was the 11th straight quarter of growth.
On Thursday, the bank's chief financial officer Rafael Arana told a news conference he expected Banorte's loan book to grow by another 15 percent in 2013.
Banorte said consumer lending increased by 20 percent during the fourth quarter, while commercial loans rose 6 percent from the year earlier quarter.
Banorte shares closed up 1.23 percent at 89.53 percent.