Amazon announced Q1 earnings last night, reporting that net income had more than doubled, to $3.6 billion compared to $1.6 billion in the period a year earlier. But cfo Brian Olsavsky warned investors not to expect similar performance in Q2, as the company expects margin growth to decline when it spends around $800 million in the quarter to evolve toward one-day shipping for all Prime members, starting in North America and eventually globally. The stock was trading near flat Friday morning on the reduced profit guidance. While profit was up, sales growth continued to slow, in line with analysts’ expectations. […]