'm not familiar with this expression.  Does it mean that shares of the society were offered..floated...on the stock exchange?    
 : Yes - from  wikt:float, to float is "to issue or sell shares in a company (or units in a trust) to members of the public, followed by listing on a stock exchange."    

 ==Public ownership== 

 As of 18 February the bank remains in private hands. The public takeover will not occur until the legislation goes through Parliament. So changes to the effect that NR is nationalised or in public ownership are premature.