BUZZ-Saudi's Yansab jumps on Q2 earnings beat

** Shares in Saudi Arabia's Yanbu National Petrochemical Co (Yansab) jump 6.3 percent in unusually heavy trade to 45.90 riyals, highest level this year ** Company beat analysts' forecasts as its second-quarter net profit trebled to 689.3 million riyals ($183.8 million) because of higher production and sales; analysts had on average forecast 446.2 million riyals ** Outperforms petrochemical sector index, which rises 1.1 percent ** Saudi stock index edges up 0.2 percent (Reporting by Andrew Torchi