Shares of SeaWorld Entertainment Inc. shot up 10.4% in morning trade toward an 11-month high, putting them on track for their biggest-ever one-day gain, after the theme park company reported better-than-expected first-quarter results. The previous biggest one-day gain was 9.4% on March 17, 2016. Volume topped 2.8 million shares, already more than the full-day average of 1.7 million shares. The company went public in April 2013, at an initial public offering price of $27, a few months before the release of the documentary film “Blackfish” that fueled the backlash over killer whales in captivity. The stock hasn’t traded above its IPO price since August 2014. The stock has soared 29.2% year to date, while the S&P 500 has slipped 0.3%.