The top performing stock within the Dow Jones Industrial Average is none other than Boeing Co . Shares of the aerospace company hit a new all-time high of $208.61 Wednesday morning and the stock is up more than 33 percent since January 1 versus about 8.5 percent for the overall index. This doesn't mean it's a good move for investors to lock in a profit, at least according to Ken Herbert, an analyst with Canaccord Genuity who covers Boeing with a Hold rating and $170 price target. At current levels, Boeing's stock delivers a dividend yield of around 3 percent and is well positioned to benefit from an improving economy and favorable defense spending from the White House, the analyst said during a recent CNBC "Trading Nation" segment. On the other hand, investors have reason to be concerned with a lack of free cash flow to the upside.Source