(Sharecast News) - London's FTSE 100 was flat at 8,293.37 in afternoon trade on Tuesday.

Asia-focused bank Standard Chartered was a high riser as it unveiled its biggest-ever share buyback and lifted guidance as interim earnings beat estimates.

The company said it would buy back $1.5bn in shares starting immediately. Pre-tax profit for the first six months of the year rose 5% to $3.5bn, compared with average forecasts of $3.46bn.

StanChart said it now expects operating income to grow more than 7% at constant currency rates compared with a previous projection of between 5% and 7%.

Weir Group gained as the engineering firm reported a small rise in first-half adjusted profits and said that strong aftermarket demand had bolstered its project outlook, but said full-year revenues will likely miss forecasts.

Convatec was weaker despite confirming its full-year and medium-term guidance.

Diageo slumped after it reported a drop in full-year organic operating profit as it pointed to a weaker performance in Latin America and the Caribbean (LAC).

Chemicals company Croda was under pressure after cutting its full-year profit outlook as it pointed to a weaker-than-expected performance in the life sciences segment, with continued destocking in crop protection and consumer health.

Glencore was in the red after a half-year production update.

FTSE 100 - Risers

Standard Chartered (STAN) 774.00p 6.49%

Weir Group (WEIR) 2,018.00p 4.56%

Burberry Group (BRBY) 752.80p 2.34%

Beazley (BEZ) 671.50p 1.90%

Rolls-Royce Holdings (RR.) 447.70p 1.80%

Reckitt Benckiser Group (RKT) 4,166.00p 1.78%

Melrose Industries (MRO) 579.60p 1.58%

Admiral Group (ADM) 2,710.00p 1.46%

Centrica (CNA) 132.85p 1.45%

InterContinental Hotels Group (IHG) 8,122.00p 1.45%

FTSE 100 - Fallers

Convatec Group (CTEC) 237.00p -5.88%

Diageo (DGE) 2,423.00p -4.89%

Croda International (CRDA) 3,960.00p -3.51%

Glencore (GLEN) 414.70p -2.98%

Entain (ENT) 579.80p -2.82%

Anglo American (AAL) 2,274.00p -2.80%

Smurfit Westrock (DI) (SWR) 3,659.00p -2.32%

Sage Group (SGE) 1,065.50p -1.93%

Lloyds Banking Group (LLOY) 60.10p -1.64%

NATWEST GROUP (NWG) 366.90p -1.21%