Stocks in the U.K. rose Tuesday, headed by Shire PLC on speculation the drug maker may land an acquisition offer, and the market held its ground after quarterly economic growth in the U.K. came in at a slower rate than anticipated.

The U.K.'s FTSE 100 rose 0.5% to 335.54, building on Monday's gain of 0.2% when another drug maker, AstraZeneca PLC, jumped 14% on indications Pfizer Inc. (PFE) may step up its takeover efforts. AstraZeneca shares on Tuesday were in the loss column, down 0.7%.

But Shire climbed to the top of the FTSE's list of advancers, rising 3.9% in the wake of a Reuters report that Allergan Inc. (AGN) is getting ready to approach Shire again about a potential merger. Reports emerged last week that previous talks between Shire and Allergan about a tie-up didn't pan out. Botox maker Allergan itself is currently being pursued by Valeant Pharmaceuticals International Inc. (VRX) in partnership with activist investor William Ackman. A representative from Shire said the company doesn't comment on market speculation.

London-listed stocks held steady after the U.K. Office for National Statistics said the economy grew by 0.8% in the first three months of the year, just shy of the 0.9% growth analysts polled by The Wall Street Journal had expected. The quarterly rate was also lower than the Bank of England's estimate of 1%. Gross domestic product for the first quarter rose 3.1% on a year-over-year basis.

The pound (GBPUSD) initially dropped against the U.S. dollar after the data, to $1.6799, from $1.685 earlier Tuesday and Monday's level around $1.6809. Britain's currency has since come off its lows to buy $1.6813.

Shares of BP PLC (BP) were up 0.9% after the oil major raised its dividend to 9.75 cents a share from 9 cents a share last year. First-quarter production fell 8.5% to 2.13 million barrels of oil a day and revenue declined to $91.71 billion from $94.11 billion a year ago.