London's FTSE 250 was up 0.7% to 19,458.55 in afternoon trade on Wednesday.
Turnaround specialist Melrose Industries - which has launched a £7bn hostile bid for GKN - was in the black after releasing a response to GKN's earlier statement outlining its Project Boost strategy to return up to £2.5bn to shareholders over the next three years.
It said the project announcement was a "stark admission" of GKN's underperformance over many years, and a validation of its own diagnosis. It asserted that, hidden away was also an acknowledgement that GKN's group trading profit margin for 2017 of 7.4% was below consensus forecast.
Sirius Minerals gained after saying it has entered into a design and build contract with shaft sinking and mining contractor DMC Mining Services for the construction of the four shafts required for its polyhalite project in North Yorkshire.
Mobile satellite communications provider Inmarsat racked up health gains, recovering from losses in the previous session on the back of a downbeat note from HSBC.
On the downside, housebuilder Galliford Try tumbled as it announced a £150m capital raising to cover the impact of the collapse of Carillion. The announcement came alongside the firm's latest interims and a decision to pay out a dividend of 28p for the six months to 31 December, versus 32p in the first half of 2017.
Virgin Money was also under the cosh as RBC Capital Markets downgraded the challenger bank to 'underperform' from 'outperform', slashing the price target to 250p from 350p as it took a look at UK banks.
AG Barr shares
fizzed lower after JPMorgan Cazenove cut its stance on the Irn Bru maker to 'underweight' from 'neutral' and chopped the price target to 570p from 630p amid concerns about growing competition and the stock's premium valuation.
Provident Financial (PFG) 701.80p 6.62%
Convatec Group (CTEC) 197.00p 5.12%
TBC Bank Group (TBCG) 1,646.00p 3.78%
Melrose Industries (MRO) 220.10p 3.77%
Ferrexpo (FXPO) 282.99p 3.58%
Merlin Entertainments (MERL) 331.60p 3.53%
Sirius Minerals (SXX) 22.90p 3.33%
Hikma Pharmaceuticals (HIK) 882.60p 3.16%
Inmarsat (ISAT) 439.10p 3.05%
Babcock International Group (BAB) 650.80p 3.04%
Galliford Try (GFRD) 819.50p -17.01%
Vectura Group (VEC) 73.75p -5.57%
Kier Group (KIE) 1,040.00p -4.41%
Virgin Money Holdings (UK) (VM.) 262.40p -3.03%
Sanne Group (SNN) 614.00p -3.00%
Barr (A.G.) (BAG) 641.00p -2.88%
Tullow Oil (TLW) 171.15p -2.23%
Cairn Energy (CNE) 181.50p -2.16%
Beazley (BEZ) 530.00p -2.03%
Go-Ahead Group (GOG) 1,377.00p -1.99%