Heavy falls from engineering firm AMEC were weighing on the oil equipment and services sector on Wednesday after the stock went ex-dividend.New investors from today will no long qualify for AMEC's latest dividend, which usually leads to an automatic drop in price by the amount of the expected payout.The share price was down 3.43% at 1,129.84p by Wednesday afternoon.Meanwhile, markets were also reacting to a report in The Times which speculated that AMEC is currently lining up a deal to merge with American rival Foster Wheeler.The rumours come just two months after the firm walked away from its £700m bid for FTSE 250 engineering firm Kentz."AMEC is understood to be taking a serious look at a bigger transaction with the acquisition of a competitor that has long had a strong presence in the Scottish oil and gas industry," The Times said.The paper said that any bid would likely consist of a mix of cash and AMEC shares, potentially creating an energy services giant worth over £5bn - Nasdaq-listed Foster Wheeler is valued at around £1.8bn, while AMEC is valued at £3.4bn.Others in the London-listed oil services sector were registering losses today, including KBC Advanced Technologies, Hunting and Lamprell, outweighing gains from Wood Group and Petrofac.Top performing sectors so far todayForestry & Paper 10,900.61 +2.12%Automobiles & Parts 8,947.78 +1.84%Personal Goods 24,421.75 +1.68%Electronic & Electrical Equipment 4,248.23 +1.53%Life Insurance 6,727.23 +1.30%Bottom performing sectors so far todayOil Equipment, Services & Distribution 23,090.43 -0.85%Oil & Gas Producers 7,970.54 -0.25%Electricity 8,838.31 -0.08%BC