BOSTON - United Technologies Corp is seeing signs of stabilization in its key businesses, though the diversified U.S. manufacturer still faces difficult end markets, a top executive said on Wednesday.

The markets remain very difficult, but the downward trends that we saw in the first two quarters of the year have pretty much abated, Greg Hayes, chief financial officer of the world's largest maker of elevators and air conditioners, said at an investor conference.

He warned that the Hartford, Connecticut-based company expects the commercial construction market to remain weak into 2010 and said that sales of spare parts for aircraft would remain weak so long as airlines had large fleets of idled planes they could cannibalize for parts.

Hayes reiterated the company's forest of 2009 earnings of $4 to $4.20 per share, excluding charges. United Tech has budgeted for 40 cents per share of restructuring expenses this year, and Hayes said he anticipates another 10 cents to 20 cents per share of restructuring charges in 2010.

(Reporting by Scott Malone; Editing Bernard Orr)