ARMONK, N.Y. — IBM said Thursday it agreed to buy privately held data-compression company Storwize for an undisclosed sum.

Storwize, based in Marlborough, Mass., provides technology that can reduce the amount of physical space that companies need to store data such as files, databases and images by up to 80 percent, IBM said.

Storwize’s clients include energy, manufacturing, finance, insurance and telecommunications companies, among others.

The deal is expected to close in the third quarter.

Shares of International Business Machines Corp. fell 17 cents to $128.26 in morning trading.