Virtu Financial (VIRT) appears an attractive pick given a noticeable improvement in the company's earnings outlook. The stock has been a strong performer lately, and the momentum might continue with analysts still raising their earnings estimates for the company.The upward trend in estimate revisions for this high-speed trading company reflects growing optimism of analysts on its earnings prospects, which should get reflected in its stock price. After all, empirical research shows a strong correlation betwe ...