Glasgow-based Aggreko and Aberdeen-based oil services firm Wood Group are part of a grouping which could be promoted to the blue chip index if one of the top 100 companies is removed because of corporate activity before the next quarterly reshuffle.
As expected, Aberdeen-based FirstGroup has been demoted from the top index, along with private equity group 3i, building supplies company Wolseley, food supplier Tate & Lyle and the London Stock Exchange.
They will be replaced by miners Fresnillo and Lonmin, oil and gas services firm Petrofac and two Footsie debutants – global testing and inspections firm Intertek and investment fund Foreign & Colonial Investment Trust.
Oil and gas firms – which already account for nearly a quarter of the Footsie's value – will remain the dominant sector following the reshuffle.
First Group – which operates franchises including First ScotRail and First Great Western – has also suffered in the US, where it operates the iconic Greyhound buses among other businesses, while growth rates in UK rail have come under strain due to commuter traffic slowing in the economic gloom.
The changes take effect from 23 March.