From The Economist Espresso: A thousand cuts: American earnings

This will be a tricky year for America Inc. Bosses face a noxious combination of rising interest costs, tanking oil prices, higher wages, a strong dollar and carnage in emerging markets. The damage will be visible this coming week when 56 members of the S&P 500 index of big firms report results for the quarter that ended in December. Overall S&P 500 earnings per share are forecast to fall by 6%, according to Factset, an analysis firm. Even if you exclude oil firms, which are facing their most severe test since the oil crash of the 1990s, earnings will be flat, year-on-year. For the past half-decade American profits have been at their highest, relative to GDP, since the second world war, with firms squeezing every dime they can from a sputtering global economy. This golden era of profits is coming to an end.