The jump this year in agricultural commodities prices triggered a food crisis that led to riots from Haiti to Egypt to Bangladesh. For investors, the crisis was an opportunity to cash in handsomely from their agricultural portfolios, from equities to commodities.

No longer. Farmers reacted to record prices for crops such as wheat, corn, rice and soyabeans by planting more. The larger acreage has led to a bumper crop – and prices down 40-60 per cent from this spring’s records.