Honeywell does not seem to have got the memo that conglomerates have become achingly unfashionable. At a time when the global trend is for industrial empires to break up and generate returns by specialising in a single area of business, boss Vimal Kapur has been bulking up.

Elliott said in a letter that it had built a stake worth more than $5 billion in Honeywell, one of its largest ever, and that management should split the company into two standalone businesses focused on aerospace and automation. Shares were up 3% on Tuesday, shedding some earlier gains.

The activist investor, which has amassed a $5 billion stake, is calling for big changes. Honeywell shares were up about 5% on the news.