LONDON (TheDeal) -- European markets were mixed on Thursday, as investors waited for the Federal Reserve's decision on interest rates later in the day. There was some relief as the Swiss central bank left interest rates on hold rather than cut rates further, after downgrading the outlook for recovery next year. In the U.K., retail sales grew just 0.1% in August, excluding fuel, a slowdown from the 0.3% recorded in July. Economists are expecting weaker third-quarter growth for the U.K. economy overall.

In London, the FTSE 100 was down 0.33% at 6,208.51, while in Paris the CAC40 was flat at 4,646.50. In Frankfurt, the DAX was up 0.19% at 10,246.20.

Amsterdam listed cable investor Altice soared in early trading on confirmation of a $34.90-per-share deal to buy New York-focused cable operator Cablevision Systems (CVC) . But by mid-morning Altice had fallen back to trade barely higher than Wednesday's closing price of €24.34. The acquisition at a premium of 22% to CVC's Wednesday close, values the target at $17.7 billion.

U.K. insurer Phoenix Group Holdings (PHXXF) ticked up 2.67% to 884 pence after saying it was in non-exclusive talks to buy private equity-backed rival Guardian Financial Services, as part of the ongoing sale process of the "zombie" or closed life insurer. Guardian, which Cinven Ltd. acquired in 2011, manages portfolios of life and pension policies but does not write new business.

Rotork (RTOXY) , which makes pressure-valve actuators for the oil and gas industry, plunged 16% to 181.40 pence on a profit warning. It has been hit by deferred and cancelled orders for its products and the generally weak market conditions in the oil industry.

Theme parks operator Merlin Entertainments (MIINF)  said takings at its six Legoland parks continued to be awesome in the 36 weeks to Sept. 5, jumping 8.7% in constant currencies. But other parks were a drag on revenues, posting a 9.1% drop, as the weakness of the euro and the aftermath of an accident at one U.K. park reduced visitor numbers. Overall revenues were up 3.8% in constant currencies. Merlin was down 0.44% at 381.0 pence.

In Paris, Alcatel Lucent (ALU) announced the acquisition of Woodbridge, N.J.-based mobile internet and Internet of Things security software provider Mformation Technologies for an undisclosed price. Alcatel's share was up 0.31% at €3.22.

Royal Dutch Shell (RDS.A) was down 0.39% at 1,651.5 pence, after the Australian competition regulator questioned whether the oil major's $66 billion acquisition of BG Group (BRGYY)  could reduce the supply of gas to Australian consumers. It fears the deal might reduce incentives for Shell to develop a liquefied natural gas plant in Queensland. Gas from BG's Australian plant is being sold overseas.

In Asia, Tokyo's Nikkei 225 index closed up 1.43% at 18,432.27, while in Hong Kong, the Hang Seng finished the day down 0.51% at 21,854.63. In China, the Shanghai Composite slipped 2.10% to close at 3,086.06 while the tech-heavy Shenzhen Composite was down 1.48% at 1,685.415. In Sydney, the ASX closed up 0.94% at 5,146.82.