* May see economic "headwinds" later in year
* Stock up 13 pct this year
* Quarterly results out late Monday beat expectations
VANCOUVER, July 26 (Reuters) - Shares of Canadian National Railway Co (CNR.TO) slid more than 3 percent on Tuesday on concerns about a potential slowdown in global economic growth along with profit-taking after a rally by its stock this year.
The slide came a day after CN Rail, Canada's biggest railroad, reported better than expected second-quarter results, despite difficulties including floods in Western Canada, forest fires and mudslides. [ID:nN1E76K2GN]
Although CN did not change its earnings guidance for 2011, it did "recognize that there are some macroindicators that suggest that there could be some headwinds leading into the fourth quarter", Raymond James analyst Steve Hansen said.
"The pace of global growth is probably one thing that is weighing on investors' minds," Hansen said.
Railroads such as CN, which transport a wide cross-section of goods, from grains to minerals and consumer products, are regarded by analysts as good barometers of economic health.
"At the same time, the stock is trading at a reasonably fair valuation so there could just be some profit-taking on some of those concerns," Hansen said.
By late morning, CN's stock was down C$2.49, or 3.3 percent, at C$72.75 on the Toronto Stock Exchange. The stock has risen about 13 percent this year.
Shares of CN's smaller domestic rival, Canadian Pacific Railway Ltd (CP.TO), were off 1.1 percent at C$58.81. Both were down more than the overall market, which was 0.67 percent lower.
Brokerage Dahlman Rose earlier on Tuesday cut its rating on CN to "hold" from "buy" because the stock price had exceeded its target [ID:nWNAB3040].
CN is a favorite among analysts not least because it is one of the most efficient railroads in North America, as evidenced by its low operating ratio -- 61.3 percent -- which measures operating costs as a percentage of revenue.
$1=$0.94 Canadian Reporting by Nicole Mordant; editing by Rob Wilson