Okay, that makes sense. But then I still can't really follow kronics reasoning. Isn't it good if investors are tempted to invest in the private economy of nations that struggle with low economic growth? Why must this result in bubbles?
Well, as Kronic said, it just results in misallocation of capital. Investors should prefer to invest in countries with
strong economic growth, as they should have lower risk of default and greater returns, and should prefer to not invests in countries with weak growth, because there is more risk of default and lower returns. When banks pile into countries like Greece and Spain, believing their debt to be as risk-free as Germany's, that money has to go
somewhere, and because the risk is priced incorrectly, it ends up going into abnormally risky ventures.
In a "normal" economy, investors invest in a country if that country has decent economic prospects; the money is channelled into the areas in which investors believe growth will occur. The demand for capital from bonds and equities comes directly from businesses who will invest and expect a return on their investment. So in Germany say, Volkswagen might want to build a new factory, and investors offer money for that factory to be built, e.g. through the bond market, raising capital through equity, through private lending by banks, or using VW's own retained earnings (i.e. profits that are not paid back to investors as dividends, so in effect investors are paying by forgoing a part of their dividend). Volkswagen will take the risk of building a new factory if the cost of capital (i.e. the yield on debt and/or equity that it needs to raise from the markets or the interest rate on a bank loan; or in other words, the price that the markets place on Volkswagen's debts) is less than the expected, risk-adjusted, present-value returns on that factory. There are two important parts to the equation:
1) Expected return on investment: this is a judgement made by investors on how profitable the investment is.
2) Risk adjusted return: this is a judgement of how risky is this investment, compared to the "risk-free" investment in government bonds.
Both of these things depend on correctly judging the economic prospects of the country being invested in (to determine if the investment will make a satisfactory return), and the risk associated both with the investment itself and the government. So three things can go wrong:
1) investors can incorrectly judge economic prospects,
2) they can incorrectly judge the risk associated with the investment, and
3) they can incorrectly judge the risk associated with gov't bonds.
Now, in Greece and Spain, all 3 things happened. People falsely believed that Greece, Spain, etc will all "converge" with Germany economically, so that Greece will get more and more competitive vs Germany and eventually become a modern economy. They believed that there was little risk in investing in Greece, because the rules set up by the Euro would
without a doubt lead to convergence. And they believed that Greek government debt was just as safe as German gov't debt, partly because of this convergence, and partly because the Eurozone forbade governments from defaulting (i.e. there was an implicit underwriting of gov't debt written into the Eurozone's rules).
What that meant was, investors
overvalued investments in Greece, Spain, etc. They falsely believed that investments in Greece and Spain were safer than they were in reality. That's where the bubble comes from - people overvaluing housing, overvaluing hotels, overvaluing golf courses in Ireland, etc etc. The money that poured into Spain and Greece had to go somewhere, and it went into places that were too risky, because investors underpriced risk in those countries.
I have no idea why that would be so
What Kaiserguard said. But looking at it from a different angle to him, you could say that if investment prospects in the private sector are really, really dire, and thus returns on equities are pathetically low, then investors will pile into government bonds instead. After all, where else can they go? This extra demand for gov't bonds will drive gov't bond yields down.