* Retailers up; M&S, Next post forecast-beating results

* Banks rebound from previous sessions losses

* U.S. Federal Reserve decision eyed at 1915 GMT

By Harpreet Bhal

LONDON, Nov 4 (Reuters) - Britain's top shares added 0.9 percent by midday on Wednesday, boosted by gains in retailers Marks & Spencer (MKS.L: Quote, Profile, Research) and Next (NXT.L: Quote, Profile, Research), which posted forecast-beating results, while financials and miners also rose.

By 1144 GMT the FTSE 100 .FTSE was up 44.01 points at 5,081.22, clawing back some losses from Tuesday when the index fell 1.3 percent to hit its lowest closing level in a month.

Next (NXT.L: Quote, Profile, Research) climbed to the top of the blue chip gainers list, up 6.2 percent after the high street retailer reported higher-than-expected third-quarter sales and upgraded its sales and profit guidance for the balance of the year. [ID:nL448585]

Rival retailer Marks & Spencer (MKS.L: Quote, Profile, Research) put on 5.8 percent, after it reported flat first-half profits towards the top end of expectations as tight management of costs and stocks offset weak sales.