More than 50 oil and gas companies are now listed on the London AIM exchange. Of the 283 stocks traded on the Alternative Investment Market, some 19% are those of oil and gas companies.

These, plus mining-company stocks, represent 50% of all stocks traded on AIM now, according to Tim Redfern, associate director, corporate finance, for nominated advisor Evolution Securities, speaking at a recent conference hosted by Haynes & Boone LLP law firm.

Meanwhile, of all AIM-listed securities, 12% are those of U.S.-based companies, including Energy XXI, which has been an active acquirer in the Gulf of Mexico and on the Gulf Coast; Frontera Resources, which has a focus abroad; and Centurion Energy, which has been bid on for acquisition by UAE-based Dana Gas.