Shareholders in the 60-year old company, which provides vehicle manuals for motorists, will receive 700p in cash for each share they hold, a 62% premium on Haynes Wednesday closing price of 431p.
The firm said its directors intend to unanimously recommend the deal to investors, who will vote on whether to approve the deal at a meeting in either March or April.
Haynes originally put itself up for sale in November following the death of its founder John Haynes shortly before its 60th anniversary.
“The Haynes Board believes that the markets it serves have great potential for Haynes' future growth and development, and that a combination with Infopro Digital will provide Haynes with the scale, capabilities and resources to ensure that it stays at the forefront of these markets and maximises its potential”, said Haynes chairman Eddie Bell.
He added that the Infopro offer presented “an attractive opportunity” for investors to “crystallise an immediate and certain value in cash for their shareholdings, at a significant premium to current and historical share price trading levels”.
The shares were 59.5% higher at 687.5p in late morning, a 1.8% discount to the offer price.