If Mr Kozlov's clean-up continues, the biggest obstacle may be over-regulation.

ECONOMIST: Russian banks

In a big survey of business perceptions this year the number of firms that reckoned over-regulation was an obstacle to success fell from 62% in 2009 to a (still high) level of 55% in 2012.

ECONOMIST: Bagehot

The biggest single obstacle to a Serbian clearing of minds is the continued rule over rump-Yugoslavia of President Slobodan Milosevic.

ECONOMIST: A little gleam of law in Serbia

One obstacle is that Spain's euro-zone partners can't agree over whether the country needs more austerity (the German view) or less (the view of most of the rest).

WSJ: Euro Zone Takes Stock of Crisis-Fighting Arsenal

The perennial idea of a transatlantic free-trade area sounds better but may well run into the obstacle of American domestic politics: with free-trade-sceptical Democrats taking over Congress, it is not an auspicious time for clinching trade deals.

ECONOMIST: Germany's role in Europe is changing

Few market theorists have detected supernatural forces at work in spurring the more-or-less straight line move that the major indexes have traced in recent weeks, even though the market has walked over every obstacle placed in its path, be it European debt, Egyptian unrest or good old-fashioned domestic unemployment.

FORBES: Fed And Treasury Leave Devilish Prints On Bull Market