Shares in the Dublin based clinical trials group Icon have plunged after a warning by it that sales will be at the lower end of guidance this year.

The shares closed USD 2.55, or 9.21pc, lower last night at USD 25.14 after the group's comments and second-quarter results.

It reported a marginal increase in earnings for the second quarter, as revenues grew by 2pc over last year.

However, it also said it now expects its final results for 2010 will be at the lower end of the guidance range given in February.

Icon has reported net profit of USD 22.87 million or 38c per share.

On average, analysts had expected the group to earn 37c per share for the quarter.

Net revenue for the quarter increased 2pc to USD 223.75m. On a constant currency basis revenue grew by 3.1pc.

Income from operations was USD 25.7m or 11.5pc of revenue, compared to USD 29.3 million previously, before one-time net charges or 13.3pc for the same quarter last year. Constant currency operating margin was 11.8pc. Commenting on the results, the company's chief executive officer Peter Gray said, "Our net booking of USD 320m was particularly satisfying, resulting in a strong book to bill of 1.4, and the growth in our backlog to USD 1.9 bn. "However, we are not expecting revenue growth to respond quickly to these awards, and as a result we now anticipate that the outcome for 2010 will be at the lower end of the guidance range given in February."