In a statement, the group - which is run by veteran US activist investor Nelson Peltz – said its stake was valued at around £736mln as of last night’s close.
The firm noted that it recently beefed up its stake in the FTSE 100-listed company – which changed its name from Wolseley in 2017 to reflect its focus on its US operations - by splashing out around £250mln at an average price of 52.85p a share.
The US group said: “Trian believes that Ferguson is an attractive business that trades at a discount to comparable US peers.”
Trian added that it has contacted members of Ferguson's management team and “looks forward to working with them to explore and implement initiatives that it believes can create long-term shareholder value.”
Move to US listing?
The Evening Standard said Peltz is expected to ask Ferguson to scrap its UK stock-market listing and move to an American listing where its shares could possibly be worth more.
It quoted a Ferguson spokesman as saying: "We welcome dialogue with Trian, as we do with all our shareholders."
In afternoon trading, shares in Ferguson were with a 6.3% rise to 5,646p.
Ferguson shares dropped earlier this week after the firm failed to win investors over with a US$500mln share buyback as the market reacted with disappointment to a slowing in organic sales growth in the third quarter.
The group generated revenue of US$5.3bn in the three months to 30 April, which was up 6.2% compared to the same period last year, or an increase of 2.7% on an organic basis.
Ferguson also confirmed that non-executive director Geoff Drabble, best known as former chief executive of fellow FTSE 100 constituent Ashtead Group PLC (LON:AHT), would step up to the chairman’s role at its annual shareholder meeting in November.