BUZZ-Boeing Co: Dreamliner costs worry investors
** Aircraft maker's shares down 0.7 pct at $126.26
** Q3 operating margin in company's commercial aircraft unit falls to 11.2 pct from 11.6 pct, reflecting effect of deliveries of lower-margin 787 and 747 aircraft
** Analysts express concerns over signs of rise in costs for 787 Dreamliner
** A relatively small increase in company's full-year cash flow outlook and higher deferred production costs for 787 "will increase the bear calls," Sterne Agee analyst Peter Arment says
** Up to Tuesday's close, stock had risen about 4 pct in past 12 months, while S&P 500 index had risen about 11 pct
** Graphic on Boeing's earnings (link.reuters.com/xud33w)
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