Global research and information technology company Gartner Inc. is expanding its Stamford headquarters, with plans to add 400 jobs over the next five years.

Gartner CEO Gene Hall said the company added 300 jobs in Connecticut over the past five years and is accelerating hiring as it expands its sales recruiting organization.

"Gartner has a sustained track record of double-digit growth," Hall said this week.

"As demand for our services continues to grow, we plan to expand our workforce in our corporate headquarters with a range of exciting new career opportunities."

Gartner currently employs about 1,200 people in Stamford and another 100 around the state. The company has a global workforce of 15,000 people.

The company will lease an additional 36,000 square feet of space in the city to accommodate its growth plans.

Connecticut's Department of Community Development provided a $5 million loan to Gartner for leasehold improvements and other expenses.

All or part of the loan may be forgiven if the company meets job-creation targets.