Wood Group was under heavy selling pressure on Thursday afternoon, providing a drag on the oil equipment, services and distribution sector.Shares in the energy and power services giant were down 4.42% at 779p before the close after the family and charities of Sir Ian Wood, the former Wood Group Chairman, sold over 16.3m shares in the firm at 775p each.The £127m sale by Sir Ian Clark Wood's 1997 Discretionary Trust and "certain members" of the Wood family equated to a 4.4% stake in the company. Nevertheless, Sir Ian did not sell any of his own 2.4% interest in the firm.The former Chairman, who announced his retirement in July, has "no current intention to sell or transfer any of his Wood Group shares", according to Credit Suisse and JP Morgan who handled the sale.Top performing sectors so far todayPersonal Goods 20,541.99 +2.81%Industrial Metals & Mining 2,480.90 +2.78%Mining 18,267.09 +2.69%Industrial Transportation 2,409.58 +2.42%Fixed Line Telecommunications 2,728.57 +2.29%Bottom performing sectors so far todayTechnology Hardware & Equipment 935.72 -1.04%Tobacco 37,383.03 -0.17%General Retailers 1,960.06 -0.16%Oil Equipment, Services & Distribution 24,107.74 -0.04%Beverages 13,473.92 -0.02%BC