(Updates with details and background)

Sept 24 (Reuters) - Buyout firms Vista Equity Partners and Blackstone will purchase collaboration-software maker Smartsheet for $8.4 bln in one of the largest take-private deals this year, the companies said on Tuesday.

Vista and Blackstone have offered $56.50 in cash for each share of Smartsheet, which represents a premium of 24.6% to the stock's closing price on July 17, when Reuters first reported that Smartsheet had tapped investment bankers after attracting acquisition interest from the buyout firms.

Smartsheet shares were up 6.1% in pre-market trading at $55.1.

Private equity firms are targeting acquisitions in the technology sector this year, driven by the strong expectation of an interest rate cut by the U.S. Federal Reserve after elevated interest rates weighed on leveraged buyouts in 2023.

Previously, Silver Lake had completed the largest take-private deal of the year in April by acquiring talent and entertainment agency Endeavor Group Holdings for $13 billion, according to LSEG data.

The Smartsheet deal is expected to close in the fourth quarter and includes a 45-day "go-shop" period that will expire on Nov. 8, during which the company and its advisors can weigh proposals from other interested parties.

(Reporting by Rishi Kant in Bengaluru; Editing by Tasim Zahid)

((Rishi.Kant@thomsonreuters.com;))