Failing to fly high like the S&P 500, which climbed about 1.7%, shares of JetBlue Airways (NASDAQ: JBLU) faced formidable headwinds and sank about 15% through the first half of 2018, according to data from S&P Global Market Intelligence. Pessimism from Wall Street analysts covering the stock was compounded by a negative market response to the rise in oil prices.By several metrics, there were reasons for investors to celebrate in the first six months of the year.