Shares in Saudi Arabia's Advanced Petrochemical , first Saudi petrochemical producer to estimate whole-year 2017 earnings, drop 3.4 percent to 41.95 riyals in heavy trade

Company said estimated annual net profit fell to 631.1 million riyals ($168.3 million) from 731.9 million riyals in 2016; revenues rose 11.2 percent

Profit had risen year-on-year in the two previous quarters. Company blamed profit drop for whole year on increase in feedstock costs; propane increased 38 percent, propylene 70 percent

Stock drops below technical support on October low of 42.50 riyals; if break is confirmed by second straight daily close, would trigger major double top formed by last year's peaks and pointing down to around 38 riyals

Saudi stock index rises 0.9 percent (Reporting by Andrew Torchia)

© Reuters News 2018