There is no sign and not even a visible street address outside the Miami office of money manager Thomas Herzfeld.

I'd appreciate it if you don't mention where we are, Herzfeld, 61, told Reuters during a break from trading one recent afternoon.

Explaining the premium he puts on privacy, he uses only a PO box as his business address, Herzfeld said he received death threats from Cuban Americans 12 years ago when he launched a fund that provides his clients with a back-door way to invest in Cuba.

Miami is the heartland of opposition to Cuban leader Fidel Castro and money, or virtually anything else to do with the island, can stir controversy in its hardline Cuban exile community.

Herzfeld has enjoyed a good deal of success with the Herzfeld Caribbean Basin Fund, made up of U.S. and Latin American companies he thinks could reap big benefits if the longstanding U.S. trade embargo against Cuba is finally lifted.

The Herzfeld Caribbean Basin Fund is a closed-end investment company with a fixed capital structure and a fixed number of shares. It trades on the Nasdaq under the symbol CUBA.

It is a relatively small piece of the $100 million he has under management, with assets of less than $14 million. But it has seen a 95 percent gain in net asset value and a nearly 80 percent gain in its share price since inception.

At the end of July, the share price traded at $7.05. But it jumped to an all-time high of $9.50 on August 2, two days after word that Castro had handed over power temporarily to his brother due to surgery to stop intestinal bleeding.

Herzfeld acknowledges that the Communist state that Castro built on the doorstep of the United States won't necessarily disappear when Castro makes his final exit from power. And there are many risks to betting on a lifting of U.S. trade barriers with the island.

RAISING THE STAKES

He is convinced the days of the economic embargo are numbered, however, and took the first step earlier this year toward raising the stakes in his Cuba bet by filing a registration statement with U.S. regulators for a second Cuba fund that would allow for direct investment in Cuba itself.

Herzfeld declined to discuss the new investment company dubbed The Cuba Fund, Inc., saying U.S. Security and Exchange Commission rules prohibit him from doing so.

But the fund, which could be launched whenever the embargo seems likely to end, could potentially be much bigger than the Caribbean Basin Fund, with hundreds of millions of dollars in assets.

As he prepares to swoop down on Cuba, and profit from the demise of Castro's regime, the soft-spoken Herzfeld might be described as the friendly face of vulture capitalism.

He said he preferred to think in terms of the American Eagle, however.

Of course, the primary investment objective is to make money for the shareholders. But I want to be involved in rebuilding Cuba, a free Cuba, he said.

The biggest holding in the Herzfeld Caribbean Basin Fund is Florida East Coast Industries, which accounts for nearly 19 percent of its assets. The company runs a railroad between Jacksonville, Florida, and Miami called the Florida East Coast Railroad.

Herzfeld Caribbean Basin, in which Herzfeld says he is the biggest single shareholder with about 3 percent of outstanding shares, closed on Friday at $7.85.

Cuba