Nigerian stocks fell the most in over a month as political tension rises less than two weeks before a presidential election and as oil slumped to a six-year low. The Nigerian Stock Exchange All Share Index dropped 2.6 percent to 29,929.56, at the 2:30 p.m. close in Lagos, the commercial capital. That’s the worst performance since Feb. 12, extending the gauge’s loss this year to 14 percent. U.S. oil futures slumped to the lowest level since March 2009. “We’ve always expected that as the elections draw near, investors will get cautious and pull out,” Seun Olanipekun, a Lagos-based analyst at Investment One Financial Services Ltd., said by phone. “That’s the major reason for the fall. The consumer names, the banking names, the oil and gas names — all have significantly declined.”