Jesper Koll is leaving JPMorgan Chase & Co. after running the firm¡¯s equity-research team in Tokyo for more than five years.

Koll resigned at the end of March to pursue a ¡°new career opportunity,¡± he wrote in an internal memo obtained by Bloomberg, without giving more details. JPMorgan¡¯s management team is working on the transition, Koll said in the memo. Yukako Yoshino, a spokeswoman for the bank, declined to comment.

JPMorgan hired Koll, 54, to head its Japanese stock strategy team in November 2009. The former chief economist at Merrill Lynch & Co. and hedge-fund manager is known for his enthusiasm for Japan and its equity market, a view that¡¯s become more common since 2012 as the Topix index rallied 87 percent under Prime Minister Shinzo Abe.

¡°I am convinced Japan stands at the beginning of a New Golden Age,¡± he wrote in the memo, dated Monday. ¡°I know that many of you share my Japan bullishness.¡±

The world¡¯s third-biggest economy is beginning to enter a self-sustaining recovery, Koll told Bloomberg on April 1. Stock valuations are attractive and earnings growth will outpace the U.S., he said, singling out bank shares as the biggest beneficiaries of improved domestic demand. The Topix Banks Index gained 7.9 percent since the interview, compared to 3.5 percent for the broader index.

¡°One of the things you learn after 20 years in this business is who is very good and who¡¯s not,¡± said Jeff Everett, a lead portfolio manager at Wells Capital Management Inc. who has known Koll for years. ¡°He¡¯s always been good. It¡¯s a huge win for wherever he¡¯s going next.¡±

In the memo to colleagues, Koll recalled a speech in 2012 in which he described the skepticism he faced as ¡°the last Japan optimist,¡± comparing it to what¡¯s encountered by people who believe that Elvis Presley is still alive.

The Topix trailed global developed-market peers for seven of the 10 years through 2011 as policymakers struggled to beat deflation, before outperforming them for the next three years.

¡°As luck would have it, Japan turned out to be as capable of revival as some of the King¡¯s riffs,¡± he wrote.

Japan¡¯s economy grew an annualized 1.5 percent in the three months through December from the previous quarter, after shrinking for two quarters following a sales-tax increase in April last year.