It's been something of a rollercoaster week for Elan, the Irish pharmaceuticals group which trades primarily in New York.

First, news that the Securities and Exchange Commission (SEC) was sceptical about the group's accounting practices - which, it felt, inflated reported earnings - sent investors running for cover and the share price tumbling close to 10 per cent, piling on the misery in what has already been a poor year for the share price.

Just for once, however, timing was on Elan's side. The letter expressing the SEC's concern was issued in January, but only became public yesterday. Within hours, the group announced that it had successfully concluded tests which reversed in mice a possible cause of Alzheimer's disease.

The shares rallied in late trade on that turbulent Wednesday and continued their recovery to finish the week at $31.25.