The FTSE 250 was up 0.75% at 19,857.60 at 1540 BST.
Shares in Lloyd’s of London insurer Beazley topped the list after the company lifted annual guidance on Friday on the back of higher cyber risk premiums.
Beazley said it now expected its combined ratio to be in the high 80s – a level below 100% indicates an underwriting profit.
It reported a first half pre-tax profit of $22m, down from $167m a year earlier, as the firm took losses on its investment portfolio.
“A challenging investment environment has impacted profit; however I’m delighted that we have achieved our best combined ratio at a half year since 2015,” said chief executive Adrian Cox.
Professional services firm JTC rose after reporting “record new business growth” in the six months ended 30 June.
JTC reported “a strong performance across the group” and said it had met all of its well-established guidance metrics, with 8-10% net organic revenue growth and an underlying earnings margin of 33-38%.
The FTSE 250-listed group said organic growth was driven by “record new business wins” of £12.6m, up 22% year-on-year, with a new business pipeline at the period end of £52.2m, 15% higher than at the same time a year earlier. It added that its performance in June was “strong”, giving “good momentum” going into H2.
FTSE 250 – Risers
Beazley (BEZ) 518.00p 8.60%
Polymetal International (POLY) 210.00p 7.14%
Ferrexpo (FXPO) 133.50p 5.37%
JTC (JTC) 748.00p 5.35%
Lancashire Holdings Limited (LRE) 420.60p 4.73%
4Imprint Group (FOUR) 3,100.00p 4.73%
Workspace Group (WKP) 591.00p 4.42%
Derwent London (DLN) 2,924.00p 3.84%
ASOS (ASC) 1,163.00p 3.56%
Big Yellow Group (BYG) 1,423.00p 3.42%
FTSE 250 – Fallers
Aston Martin Lagonda Global Holdings (AML) 465.60p -12.08%
Network International Holdings (NETW) 192.80p -2.13%
Serco Group (SRP) 181.20p -2.11%
FirstGroup (FGP) 130.40p -1.95%
Currys (CURY) 71.10p -1.93%
Clarkson (CKN) 3,465.00p -1.56%
HarbourVest Global Private Equity Limited A Shs (HVPE) 2,235.00p -1.54%
Synthomer (SYNT) 233.00p -1.35%
Vietnam Enterprise Investments (DI) (VEIL) 656.00p -1.35%
Essentra (ESNT) 245.50p -1.21%