Capital Group Cos., one of downtown L.A.’s biggest tenants, made a commitment last month to stay at 400 S. Hope St. for 15 more years after its lease runs out in 2018.

The deal with landlord CBRE Investors includes an expansion. Capital Group will take an extra floor, bringing its occupancy to 165,000 square feet from the 140,000 square feet in its current deal. Sources said the latest transaction is valued at close to $100 million.

The expansion is to accommodate new associates in sales and distribution as business grows, said a spokeswoman for Capital Group. The firm will move into the additional space next year.

The 26-story, 701,500-square-foot Class A office building is roughly 90 percent leased. It is the location of CBRE’s corporate headquarters.

Todd Doney, John Zanetos and Will Adams of CBRE represented the landlord. John McRoskey and Frank Scott of Jones Lang LaSalle Inc. represented Capital Group.

Capital Group signed another big renewal lease just across the street at 333 S. Hope in March, agreeing to stay in the 323,000 square feet it rents from landlord Brookfield Property Partners at Bank of America Plaza for 15 more years.