Shares of aircraft leasing firm Avolon Holdings (AVOL) have been flying through some turbulence since going public less than a month ago. Avolon made an initial public offering at 20 a share, but the stock has yet to trade above that level. Shares have ranged from 18 to 19.90 as the stock tries to get back to its IPO price. So the stock has yet to form a base pattern. A weak market has contributed to Avolon’s struggles.