The dangers and drawbacks of Quantitative Easing
Generally, quantitative easing (central banks buying up bonds with newly created money) is expected to boost economic growth as it has the following effects:
Buying up large quantities of bonds suppresses long-term interest rates. This is extremely important, as long-term interest rates are far more important for economic growth than short-term interest rates.
Substantially forcing down interest rates – particularly yields on government bonds – encourages investors to seek refuge in riskier investments, because the return is higher (but the risks are also higher). In other words: Quantitative easing generates an increase in investment in stocks, company bonds, and suchlike.
The best thing, naturally, would be if lower interest rates were to immediately prompt more borrowing and less saving, but it can also be encouraged indirectly. Higher stock and bond prices improve the balance sheet position for many parties. If too many old debts were the reason for not borrowing any more, that situation changes if asset values rise and particularly if housing prices rise as well.
Generally, the currency of the country implementing quantitative easing depreciates, as it becomes more appealing for domestic investors to invest in the country in question, due to lower interest rates. There is also more money in circulation, part of which will probably be invested elsewhere. A cheaper currency then aids foreign trade.