The FTSE 100 dropped 61 points at the open as BP and Shell slipped due to falling oil prices.
Tech investors Scottish Mortgage Investment Trust and Polar Capital Technology Trust also fell after a rough night for the Nasdaq.
Greggs shares are down nearly 10% after results showed sales growth slowing at the bakery chain.
Direct Line Insurance, which agreed to be bought by Aviva in December, posted strong results, reporting growth and a recovery in motor insurance profits.
And Abrdn saw its first profit growth in three years and announced a strategy shift to strengthen its wealth and investments business.
