Adds Bunzl comment in paragraph 4, updates shares in paragraph 7

June 15 (Reuters) - U.S.-based activist investor Elliott Investment Management has taken a roughly 5% stake in business supplies distributor Bunzl BNZL.L, a person familiar with the matter said, sending the British group's shares up nearly 4% on Monday.

The stake would put Elliott among Bunzl's biggest investors, LSEG data shows. Schroder Investment Management is Bunzl's largest shareholder with 5.13%, followed by Mawer Investment Management at 4.99% and Capital Research Global at 4.94%.

Elliott is pushing Bunzl to buy back shares worth up to 10% of its market capitalisation over the next 12 months and conduct a review focused on its North American business to lift the group's valuation, the source said, confirming an earlier report by Bloomberg News.

"Bunzl is committed to engagement with all shareholders and is focused on creating shareholder value," a company spokesperson said in an emailed statement.

Elliott did not immediately respond to a request for comment.

The move adds to Elliott's growing presence in Britain, where it holds stakes in BP BP.L and the London Stock Exchange Group LSEG.L, where it has pushed for buybacks and operational improvements.

Bunzl shares were up 2% by 1320 GMT, having risen as much as 3.7% to 2,632 pence earlier, valuing the group at £8.23 billion ($11.05 billion). The stock has risen by a quarter this year.

Bunzl, which supplies everything from stationery to food packaging, is attempting to turn around its North American business, which accounts for more than half of its revenue.

It has cut costs and reshaped its product mix in the region, after weak demand and execution weighed on margins.

In April, Bunzl reported a 2% rise in first-quarter underlying revenue and reiterated its outlook for 2026, despite geopolitical and macroeconomic uncertainties.

($1 = 0.7448 pounds)