IT watcher Forrester Research Inc. says it plans to buy rival Giga Information Group Inc. in a $51 million deal. Forrester has agreed to pay $4.75 each for all outstanding shares of Giga.

The deal has been approved by the respective boards, but awaits regulatory approval. Forrester says it would get 900 new customers and greater depth in analyzing the technology needs of governments and financial markets.

Consolidation in the IT research market comes as little surprise, given that many corporate-technology buyers have clamped down on spending. In its most recent quarterly report, Giga said that its revenue for 2002 would be off by 10%.

Forrester also has been hard hit by the downturn in tech spending. Its revenue for the first nine months of 2002 fell to $73.4 million from $125.5 million for the same period the year before.

Forrester, based in Cambridge, Mass., employs 367 worldwide, while Giga, which also operates out of Cambridge and which introduced its first advisory services in 1996, employs 275. A Forrester spokesman said it's too early to say whether any substantial job cuts or facilities closings would follow in the wake of the merger.