BUZZ-Yanbu Petrocehmical jumps on strong Q1 earnings

** Shares in Yanbu National Petrochemicals (Yansab) jump 4.2 percent to 42.70 riyals ** Company reported 41 percent jump in net profit to 401.9 million riyals ($107.2 million), beating analysts' average forecast of 310.8 million riyals ** Attributed increase to lower feedstock costs and higher operating efficiency ** Of 14 analysts polled by Reuters, 10 rate stock "buy" and rest "hold" with average target price of 41.55 riyals ** Saudi Arabia's stock index edges up 0.1 percent (Reporting by Celi