The survey, by Merchant International Group, a London-based corporate intelligence and research consultancy, measures business perceptions of corruption, bureaucratic delays and other factors which it calls grey area dynamics, and combines this with more conventional political risk analysis.
Based on responses from more than 2,500 US and UK companies, it focuses on emerging markets where foreign investors are active. Venezuela, Mexico, Pakistan and Brazil are rated as the second, third, fourth and fifth riskiest markets.
When the survey was last conducted two years ago, Nigeria was rated most risky.
Stuart Poole-Robb, chief executive of MIG, said: If companies carry out country risk analysis just using traditional credit agency ratings or macro-economic and political risk studies, they will get a total distortion of the real risks they will encounter when operating overseas.
Grey area dynamics also include counterfeiting and unfair competition by state-owned or other local companies, and can have a much bigger effect on companies operating overseas than macro-economic and political risks.