Federal Reserve Chair Janet Yellen's assets rose in value by at least 8 percent during 2013, raising their total to between $5.3 million and $14.1 million, her latest financial disclosure shows.

Yellen's biggest asset is a trust fund she set up in 1992 with her husband, George Akerlof, a Nobel Prize-winning economist. The value of the trust fund is estimated at between $1 million and $5 million.

Yellen's assets have likely been driven up in value by a rebounding economy and a rising stock market. In 2012, her disclosure form estimated her assets at between $4 million and $13 million.

Some of Yellen's listed assets belong to her alone; others are co-owned with Akerlof.

The disclosure documents provide only a broad range rather than a specific figure for total assets.