Shares in low-cost airline EasyJet (LON:EZJ) will fly back into the FTSE 100 index as part of the latest quarterly index review. Meanwhile, betting firm Entain (LON:ENT) and housebuilder Persimmon (LON:PSN) will exit the index and be relegated to the FTSE 250. All changes will be implemented at the close on Friday 18 September and take effect from the open on Monday 21 September.
EasyJet flies in, briefly
The reason behind EasyJet rejoining the premier index of UK stocks is the Apollo bid, which caused the share price to spike. Apollo offered 715p per share, seeing off a rival bid from Castlelake, but the takeover depends on regulatory approval.
Delaware-based Apollo hopes to complete the deal early next year, but it needs the approval of European regulators and has had to delay sending the scheme document to shareholders.
Assuming the deal goes ahead without any last-minute hitches, EasyJet will leave the index in 2027. The London Stock Exchange Group (LON:LSEG) will then have to find another stock to replace it.
Joining EasyJet in the big-cap benchmark is independent North Sea oil and gas producer Ithaca Energy (LON:ITH). Ithaca’s shares have had a strong run year-to-date, gaining more than 60% on the strength of Brent crude.
Entain and Persimmon head for the exit
Shares in betting firm Entain have performed poorly so far in 2026, losing almost a third of their value. This is despite the firm posting respectable H1 results with online revenue growing faster than expected driven by the UK and Australia.
The second stock to exit the FTSE 100 this month is housebuilder Persimmon, whose shares have drifted down 15% year-to-date. Therefore, its market cap of £3.7 billion means it no longer qualifies for inclusion in the large-cap list.
Unlike most of the housebuilding sector, Persimmon has posted positive trading updates this year. In March, it confirmed its FY26 earnings targets saying conditions were ‘supportive’ for the new-build market. It then raised its FY26 completions target in August, but warned rising input costs could crimp margins.
Other FTSE 250 joiners
Joining the mid-cap index with Entain and Persimmon are Pinewood Technologies (LON:PINE), Seraphim Space Investment Trust (LON:SSIT) and Volex (LON:VLX). Like EasyJet, motor dealer software platform Pinewood is the subject of a takeover offer, which explains the shares’ performance and their promotion to the index.
Meanwhile, shares in Seraphim have gained 54% this year driven by investor interest in space technology and the SpaceX IPO. The firm has also raised capital through a C share placing, increasing the number of shares in issue.
The final joiner Volex makes power and data connectors and has been a beneficiary of the rollout of datacentres. The firm raised its FY26 earnings guidance in March and raised its FY27 guidance last month due to ‘elevated’ demand for its products.
FTSE 250 leavers
Leaving the FTSE 250 for the small-cap index are luxury carmaker Aston Martin Lagonda (LON:AML) and software firm GB Group (LON:GBG). Shares in Aston Martin have fallen 45% year-to-date as it stumbles from one liquidity crisis to another.
Since coming to market in 2018, the company has burned through over £3 billion of cash despite successive capital raises. The firm faces cost input inflation, a soft sales environment and punitive US tariffs on imported vehicles.
Meanwhile, location and ID verification software provider GB Group warned last month of ‘higher than expected attrition’ in the US. Just weeks earlier the company had reported trading in line with expectations, so the change in tone caused a sharp sell-off in the shares.
