(ShareCast News) - Charles Stanley upgraded Ashtead to 'buy' from 'accumulate' following the company's first-half results on Wednesday.It noted that the shares sold off on negative sentiment and signs of weakness at competitors, as it highlighted the company's better-than-expected interim numbers.The brokerage pointed out that Ashtead shares are down 20.4% year to date compared with a sector fall of 21.9%."Concerns over the impact of the lower oil price on the business and the potential for overcapacity in the US rental equipment market appear to have been overplayed, and the market is expected to continue to grow at circa +7% for the foreseeable future."Charles Stanley said earnings per share of 21p were 9% above consensus.At 1437 BST, shares in the industrial equipment rental firm were up 6.9% at 979.50p.