Wall Street Momentum Traders Are Having Best Run in Three Years

A lot of things got worse in September. The government shut down, US job prospects dimmed, and debates around central bank autonomy grew deafening.

And yet in commodities, stocks and foreign exchange markets, the month will go down as a time when a simple bet that winning trades continue to win saw its best stretch in three years.

Gold surged 12%, extending its upward march for the eighth time in nine months, while the Japanese yen slid further against the dollar. Stocks from New York to Seoul built on a months-long advance that has now added around $35 trillion ...