Valero Energy (VLO) shares soared 3.4% in the last trading session to close at $148.67. The move was backed by solid volume with far more shares changing hands than in a normal session. This compares to the stock's 12.1% gain over the past four weeks.The surge can be attributed to Valero Energy’s strong foothold in the refining sector and an expected improvement in refining margins in the United States. A decline in domestic refining capacity, driven by the closure of major refineries such as Phillips 66’s ...