Figures from the 18-country region showed retail sales fell 1.6% in December, offsetting a rise the previous month and exceeding the 0.5% fall forecast by economists. It also represented the biggest monthly decline since May 2011.
But the FTSE-100 Index shrugged off the figures to rise 8.6 points to 6457.9 as investors moved to pick up bargains in the wake of the recent sell-off.
The mood in London was helped by more encouragement from the dominant services sector following another strong reading in the Markit/CIPS purchasing managers' index.
While the score of 58.3 represented the third month in a row of slowing growth, the performance was still well above the long-run trend.
The pound failed to receive a boost, remaining largely flat at 1.63 US dollars and 1.21 euros.
One of the biggest gains in the top flight came from RSA Insurance as the market reacted to news that former Royal Bank of Scotland boss Stephen Hester has taken over as chief executive.
RSA shares finished 3% higher after Tuesday's announcement and were up by another 5% or 4.6p to 103.6p.
Temporary power supplier Aggreko fell 26p, or 1.65%, to 1548p amid reports five million shares had been sold by an institutional investor.
Chip designer ARM Holdings rose 17.5p to 892.5p as investors returned to the company in the wake of a sharp sell-off on Tuesday after its warning of slower demand for high-end smartphones.
Fund supermarket Hargreaves Lansdown topped the FTSE 100 Index fallers board despite results showing an 11% rise in half-year profits to £104.1 million, a performance boosted by demand following the Royal Mail flotation.
The figure missed City expectations as Hargreaves said lower interest rates on cash holdings caused profits growth to lag behind a 43% hike in funds under management.
Shares were 152p lower at 1345p, a fall of 10%.
GlaxoSmithKline shares rose 2% or 25.5p to 1579.5p as it returned to revenue growth after two years of falling sales, albeit with a modest 1% rise.
Fashion chain French Connection shares rocketed by 19% - up 7p to 43p - after it said robust Christmas trading was expected to lead to lower-than-feared annual losses of around £4.7m, down from £7.2m the year before.
The biggest FTSE-100 risers were Tullow Oil up 56p to 849.5p, RSA Insurance ahead 4.6p at 103.6p, Associated British Foods 121p stronger at 2883p and William Hill 9.2p higher at 343.9p.
The biggest FTSE-100 fallers were Hargreaves Landsown off 152p at 1345p, Tate & Lyle down 17p at 755.5p, Sage 7.6p weaker at 407.2p and Imperial Tobacco 38p lower at 2189p.