Publishers Informa and Taylor & Francis announced a £1.1bn merger yesterday in a deal that will unite shipping newspaper Lloyd's List with a range of academic titles.

The new company, to be named T&F Informa, will publish about 2,500 subscription-based titles and arrange 2,800 events a year.

David Smith, who is to be chairman of the new group, said there was little overlap between the two firms. "This is built around enhancing revenue opportunities," he said.

Shares in both companies rose sharply yesterday.

Taylor & Francis was the best performer in the FTSE 250, with a 15% increase to 483p. Shares in Informa rose 4% to 388p, giving the combined group a market capitalisation of £1.1bn.

Some analysts questioned the rationale of the deal, however. Paul Richards, an analyst at Numis Securities, said: "This is a strange deal."

He pointed out there are very few synergies between scientific publishing and the sort of business-to-business conference organising carried out by Informa.

Others were more sanguine in the face of the increased competitive threat from open access publishers in the academic market. Malcolm Morgan at Investec called it a "fair deal for both parties".

There was some disappointment in the City over the cost savings target.

With few job cuts expected, the company is to save at least £4.6m in annual pre-tax profits by the beginning of next year with a one-off cost of £1.3m.

Peter Rigby, the chief executive of Informa, will take a similar role at the enlarged group while his counterpart at T&F, David Smith, will become chairman.

Don Cruickshank, the chairman of T&F, will remain as a non-executive director.

Under the terms of the deal, Taylor and Francis shareholders will receive 17 new Informa shares for every 10 T&F shares and will retain 49% of the merged group.