UPDATE 1-UAE's ADCB Q3 net profit lags f'cast on provisions

* Q3 net profit slides 90 pct to 44 mln dirhams

* Lags analyst f'casts for 274 mln dirhams profit

* Books Q3 provisions of 810 mln dirhams

* Warns of "challenging" markets in short term

* Stock closes down 8.3 pct, underperforms index

(Adds detail, share price reaction)

By Stanley Carvalho

ABU DHABI, Oct 27 (Reuters) - Abu Dhabi Commercial Bank ADCB.AD posted a 90 percent drop in third-quarter net profit, falling short of analysts' expectations, as the lender booked hefty provisions, sending its shares down over 8 percent.

ADCB, the sixth largest bank in the UAE by market value, posted a net profit of 44 million dirhams ($11.98 million) in the third quarter versus 447.6 million dirhams in the year earlier period, according to a statement on the bourse's website on Tuesday.

"The bank continued to set aside provisions to cover any probable loss in its loan portfolio and some investments which had a negative impact on the bank's results for Q3," Eissa Al Suwaidi, chairman of ADCB, said in a statement.

The bank warned of "challenging" markets in the short term and said it booked provisions of 810 million dirhams against bad loans. Year-to-date provisions stood at 1.7 billion dirhams.

Analysts polled by Reuters earlier this month forecast an average third-quarter net profit of 274 million dirhams. [ID:nL4403325]

Shares tumbled on the news, shedding 8.3 percent to close at 2.12 dirhams, giving up gains made since Sept. 8. The Abu Dhabi leading share index .ADI ended down 0.71 percent.

Net interest income increased to 2.41 billion dirhams in the nine months, up 35 percent over the same period last year, while operating income rose 9 percent to 3.56 billion dirhams.

The bank's gross loans stood at 119.3 billion dirhams and deposits at 83.5 billion dirhams at end-September, with the loans-to-deposits ratio at 140 percent.

Total assets stood at 158.6 billion dirhams, up 7 percent from December 2008.

(Additional reporting by Nicolas Parasie; editing by Simon Jessop)