Saudi Basic Industries Corp (SABIC), one of the world's largest petrochemicals groups, reported a 29 percent plunge in fourth-quarter net income on Sunday, widely missing analysts' forecasts.The Gulf's largest listed company earned 4.36 billion riyals ($1.16 billion) in the quarter to Dec. 31 compared to 6.16 billion riyals in the year-earlier period, SABIC said in a bourse statement.SABIC, which is 70 percent state-owned, attributed the fall in profits to lower average prices for the products which it sold, although this was partly offset by lower feedstock prices. The profit was well below the average forecast of seven analysts, who had predicted a quarterly profit of 5.50 billion riyals.