Ann DuignanJ.P. MorganDubbed “a tremendous resource” by one grateful fan, Ann Duignan holds second place for a sixth year running. The J.P. Morgan analyst downgraded Canada’s Westport Innovations from neutral to underweight in February, at $43.94. The Vancouver-based supplier of truck engines that run on liquefied natural gas had just issued its second equity offering since November 2010, which Duignan interpreted as a sign of weakness that would adversely affect the share price. She was right. In early May, after the stock had tumbled 35.8 percent, to $28.21, and trailed the sector by 26.9 percentage points, she raised it back to neutral, on valuation. The shares had climbed back to $35.21 by the end of August. “Nobody is better than Ann at ferreting out the key issues,” declares one ally. Duignan, who follows a universe of 20, currently recommends staying away from such agricultural-machinery manufacturers as Illinois’s Deere & Co. because of the drought in the American Midwest.