Investors contemplating Viacom have an Indiana Jones-esque problem. The company before them glitters – it beat second-quarter forecasts and has shares that are, on most measures, cheap. But worries lurk that to snatch it may release a big boulder in the form of its lumbering business model.

Stabilising US advertising sales are to be welcomed in a company that makes half its operating income from ads. A 6 per cent drop on last year is an improvement on the 9 per cent rate of decline registered in the first quarter and is less bad than the 11 per cent drop in US ad spending expected for this year by forecasting outfit Zenith Optimedia. This business should be at the forefront of any recovery.