Happy days are here again in the stock market - and in normal times, that means Australian dollar holders are having fun too.
Just not now.
The risk-sensitive Aussie is diverging from the S&P 500 index, and trading lower against the dollar. Some might see this as a bearish indicator for stocks, but Amelia Bourdeau, director of foreign exchange at Westpac Institutional Bank, has other ideas.
"Japanese retail investors may be the reason why Aussie's been so low," she told CNBC's Melissa Lee.
To contend with years of low Japanese interest rates, retail investors there have shifted much of their money abroad. For a long time, they had substantial holdings in European assets. But as the European sovereign debt crisis ground on, many Japanese moved money out of the euro zone and into Australian assets, Bourdeau says. And now that the euro zone is back from the brink, "data from the Ministry of Finance in Japan is showing that that trend is reversing. They're selling their Aussie assets and going back into euro."
These Japanese investors have a lot of money to move around, Bourdeau says, and their pension funds are quite easy to access, so they can have a significant impact on a currency.