The current account surplus got bigger in July as companies and individuals earned more from their overseas investments and exports increased, the Finance Ministry reported Wednesday.

The surplus expanded 4.5 percent to ¥1.86 trillion from a year earlier. The median estimate of 32 economists surveyed by Bloomberg News was for the gap to swell to ¥1.82 trillion.

The widening surplus in the broadest measure of trade reflects the willingness on the part of some Japanese to invest in overseas securities that have higher yields than those they can obtain at home.

"Income from investments has been solid," said Tomoko Fujii, head of economics and strategy for Japan at Bank of America in Tokyo.

The income surplus, the difference between money earned abroad and payments made to foreign investors in Japanese companies, rose 24.6 percent to ¥1.52 trillion, the Finance Ministry said.

The rise in the income gap "reflects investors chasing higher returns overseas and their enthusiastic investment in stocks in foreign countries," said Masami Oka, special officer for balance of payments at the ministry.

Japanese mutual funds increased the percentage of foreign assets they hold by 52 percent to ¥34.8 trillion in the year that ended July 31, according to the Investment Trusts Association of Japan.

Foreign assets now account for 44 percent of the ¥79 trillion held by the funds.

Revenue from foreign equities, bonds and debt securities makes up about 80 percent of the income surplus, according to the ministry.

Japan's low interest rates encourage investors to invest elsewhere.