Tuesday broker round-up

Bioquell: N+1 Singer upgrades from hold to buy with an unchanged target price of 112p. Investec cuts target price from 133p to 98p, while upgrading from hold to add.Circle Oil: Investec moves target price from 50p to 70p and maintains a buy recommendation.Clinigen Group: N+1 Singer ups target price from 439p to 488p and keeps a buy recommendation.Greene King: Numis upgrades from add to buy with a target price of 975p.Kazakhmys: Canaccord Genuity shifts target price from 295p to 300p upgrading from sell to hold.Phoenix Group: Barclays upgrades to equal-weight.Plexus: Numis moves target price from 364p to 372p and upgrades from add to buy.Polymetal: Canaccord Genuity ups target price from 540p to 565p and retains a hold recommendation.SIG: UBS lowers target price from 230p to 220p leaving its buy recommendation unchanged.Synthomer: Deutsche Bank raises target price from 225p to 260p upgrading to buy. SIG Synthomer Plexus