During most of March the euro had the upper hand. In the first three and a half weeks it strengthened by more than two and a half US cents, touching a four month high. Then, for no compelling reason, investors decided it had gone far enough. They knocked the euro back, halving its net monthly gain to a cent and a quarter, still worth having but not exactly stellar. The about-turn doubtless related to technical factors: it coincided with the level from which the euro had rebounded in June last year.