(ShareCast News) - Big Oil again lent its heft to the market´s advance after Russia and Saudi Arabia unveiled an agreement to collaborate in the energy space.In a statement issued at the Group of 20 meeting in Hangzhou,China the oil producers said they would set up a working group to monitor the market and draft recommendations to ensure its stability.Reports published earlier in the day had suggested that a specific deal had been brokered to freeze oil output at its current levels, which contributed to a 5% jump in crude oil futures when the headlines first began crossing traders´ screens.By the close of trading in London, Brent futures had trimmed their initial advance, finishing the day up by 1.43% at $47.51 per barrel.Although it did not find its way into the first breaking headlines, the assembled G-20 leaders also endorsed creating a global body charged with monitoring steel overproduction.That may have contributed to gains in shares of Evraz which, for the moment at least, appeared to have reached a nadir on 1 September, almost coinciding with the start of the G-20 gatherings (and after hitting its 200-day moving average).Also on the frontfoot at the start of the week was the Aerospace and Defence group, on the back of positive noises from analysts at Goldman Sachs, who reiterated their Conviction-Buy recommendation for stock in BAE Systems.The broker´s analysts believed the aerospace and defence engineering outfit was set to benefit from increased spend both in the UK and the US.Goldman also reiterated its neutral stance towards Cobham and Meggitt, emphasising the importance of the new management team (changes in the CEO and CFO roles were in progress) at the former and expectations for organic revenue growth to pick-up at the latter during the backhalf of 2016.Stock in US-exposed CRH also rose, pulling the Construction & Materials sector higher with it. Tobacco on the other hand gave back some of the previous session´s gains, while Ibstock and Polypipe Group dragged on the Household goods and Home construction sector.Top performing sectors so far todayIndustrial Metals & Mining 1,291.17 +2.50%Construction & Materials 6,322.98 +1.27%Oil & Gas Producers 7,170.08 +0.99%Oil Equipment, Services & Distribution 15,358.38 +0.91%Aerospace and Defence 4,732.08 +0.84%Bottom performing sectors so far todayTobacco 56,469.45 -1.45%Technology Hardware & Equipment 1,997.74 -1.41%Household Goods & Home Construction 16,937.07 -0.87%Mobile Telecommunications 5,108.57 -0.60%Beverages 17,128.12 -0.57%