By Barbara Kollmeyer, MarketWatch

MADRID (MarketWatch) -- Lloyds Banking Group PLC was a stand-out gainer in an otherwise flat London market on Tuesday, with shares of the bank surging on results, as BP also rose after its results.

The FTSE 100 index was flat at 6,459.70, looking at a gain for the month that won't even reach 1%. The index closed up 0.5% on the prior session.

Just a few shares seemed to be driving the London action. Lloyds (LYG) jumped over 4% after the bank said it swung to a hefty profit in the first quarter of the year, with impairment charges dropping off and no need to put money aside to cover the misselling of payment protection insurance products.

Also higher, shares of Royal Bank of Scotland Group PLC (RBS) jumped 5%.

Shares of BP PLC (BP) rose 3.6% after the oil major posted a more than threefold rise in profit for the first quarter, driven by proceeds from the sale of its Russian joint venture TNK-BP, a fall in oil and gas production and downtime at a key Indiana refinery.

On the downside in London, shares of heavyweight Unilever PLC fell 1% after the company said it will raise its stake in Hindustan Unilever, its India subsidiary, to 52.48% to up to 75%, spending around 4.1 billion euros ($5.4 billion).

Shares of Centrica PLC fell over 2% after the utility was cut to underperform from neutral by Credit Suisse, which said trading conditions for its British Gas unit have deteriorated. It noted that Centrica shares have performed well in the last 18 months.

Away from the main index, shares of Invensys PLC rose nearly 5% after Societe Generale upgraded shares to buy from hold, citing an improved investment profile and potential upside from merger and acquisition activity.

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