The problem is similar to the central banks' analyses of the output gap, which indicates whether there is an inflationary risk in the economy as a result of an excessively high level of activity or a risk of deflation. The output gap is calculated routinely by central banks around the world, and these calculations estimate the sizes that would be included in a calculation of over-valuation or under-valuation on the share markets. It can hardly be easier to calculate potential growth for the entire economy than the fundamental value of the stock market, according to critics of US monetary policy. It should be possible, at least in the case of major deviations from fundamental economic conditions, to detect imbalances on the asset markets, exaggerated valuations that could potentially give rise to monetary policy measures being necessary, even if the target for consumer prices is being followed fairly well. This is how the international discussion runs, caused by stock market developments, primarily those in the USA, with the current fears that the large downturn on the stock exchange will be followed by a deep recession. For a small, open economy like Sweden's, the possibility of affecting share prices through monetary policy restraint should be limited. The Swedish stock market is strongly correlated with that in the USA, partly because many of the companies listed on the Swedish stock exchange are multinational. In principle, however, there is good reason for taking action if we assess that large financial imbalances are being built up.
For instance, shareholding is more widespread among Swedish households and many of the major "Swedish" multinationals – in which Swedes have invested a substantial part of their shareholdings – are very dependent, directly or indirectly, on developments in the USA. Developments in the Swedish economy in recent years have shown many similarities to developments in the USA. Rapidly rising share prices, a strong GDP growth driven by both investment and consumption and an increase in indebtedness is a description that fits both the Swedish and American economies in recent years. However, the increase in economic activity began later in Sweden and has not really had the same speed as that in the USA. Moreover, the rise in Sweden was preceded by a period where adjustments following the crisis at the beginning of the 1990s had forced down investment and consumption considerably and where both the household and corporate sectors had reduced their level of indebtedness. Saving in both of these sectors was therefore at a high level and indebtedness fairly low when growth in the Swedish economy picked up. Now that economic activity is slowing down, the private sector's indebtedness is not particularly high, from a historical perspective. Furthermore, the lower interest rates will mean that interest expenditure comprises a much smaller burden for borrowers now than previously. Although the surplus in saving in the private sector has declined gradually in recent years, it only became a slight deficit towards the end of last year.