A quiet summer spell has resulted in rumours suggesting that Teva Pharmaceutical Industries may be planning a bid for the UK’s Shire which in turn has been linked with making an offer for Switzerland’s Actelion.

The rumours have been brewing for a week since Citigroup analyst John Boris issued a research note stating that acquiring Shire “would make strategic and financial sense for Teva”. He added that a deal closing before the end of the year would be modestly dilutive in 2010 and accretive to earnings thereafter.

He based this on assuming that Teva would pay the same 40% premium it coughed up for Barr and offered 40% equity and 60% in cash. Buying Barr cost $7.5 billion, but getting hold of Shire would cost considerably more, with observers putting the figure in the range of $10-$13 billion.

Teva is of course the world’s largest generics company but has been making noises that it is also interested in expanding its branded business which is made up principally by the multiple sclerosis blockbuster Copaxone (glatiramer acetate).and Azilect (rasagiline) for Parkinson’s disease. A bid for the successful specialty pharmaceutical player Shire could fit the bill.

However Shire, which gets mentioned as a takeover target every few months, could do worse than hit the merger merry-go-round itself, according to analysts at Canaccord Adams. They claim in an investor note that buying Actelion would be a "very good defensive move" by the Basingstoke-based group.

Actelion is best-known for its pulmonary arterial hypertension blockbuster Tracleer (bosentan) but also markets the Gaucher’s disease drug Zavesca (miglustat). Shire is moving its Gaucher disease compound velaglucerase alfa closer towards US approval and the analysts said that "a combined Shire/Actelion would be a very interesting company given Actelion's established network of physicians” who treat the genetic disease.

The Canaccord Adams note also argues that Tracleer would prove to be “a very useful cash cow and any questions over Actelion's long-term growth prospects would no longer be an issue”.