The "Mad Bomber" of Wall Street strikes again!

That would be Ken Heebner, legendary, if somewhat eccentric, manager of

(CGMRX) - Get Report

CGM Realty (CGMRX) and

(CGMFX) - Get Report

CGM Focus (CGMFX) funds.

He's also been called "the Savant." Either way, he's getting it done. And how.

I happened to put some money into the Focus fund during the buying opportunity in mid-August. I figured this would be a good home for some long-term cash.

I didn't figure on what would happen next. Gain so far: 50%. In two months.

Yikes! Sometimes an investment performance is so good it's scary.

Investors be warned: Heebner runs a concentrated portfolio and he takes risks. And a fund that can rocket can also do the reverse. But 50% in two months?

That's thanks to his huge bets on a few skyrocketing sectors -- like energy, commodities, infrastructure and fertilizer. Those four sectors account for more than three quarters of the fund.

His investors are also reaping the gains from another smart move. Heebner dumped financials, like the Wall Street banks, in late July.

His big bets right now include oil services giant

Schlumberger

(SLB) - Get Report

, fertilizer companies

Mosaic

(MOS) - Get Report

and

Potash Corp.

(POT)

of Saskatchewan, and big power infrastructure companies

Fluor

(FLR) - Get Report

,

Foster Wheeler

,

McDermott

(MDR) - Get Report

and

Cummins

(CMI) - Get Report

.

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As of the end of June, he also had big stakes in

Vimpel

(VIP)

, a mobile phone network operating in Russia and central Asia, miners

Freeport-McMoran

(FCX) - Get Report

and

Companhia Vale do Rio Doce

(RIO) - Get Report

and oil company

Petroleo Brasileiro

(PBR) - Get Report

.

Heebner last disclosed his holdings during interviews in August, including one on

CNBC

and one with Kiplinger's.

He could not be reached for comment for this article.

Larry Glazer, portfolio manager at Mayflower Advisors in Boston, puts it well. "It's so focused, it's almost like a sector fund. It just changes sectors from time to time," he says.

CGM Focus is now up 69% so far this year. There are no prizes for guessing that it is at the head of the class.

That's also true over the past one, five and 10 years.

Heebner supposedly earned the nickname Mad Bomber for the way he barrelled out of some stocks and into others.

He's a familiar figure around Boston's financial district. Other labels that get tossed around are Mad Genius and Mad Professor. You get the picture. Brilliant, and idiosyncratic.

It's no surprise that the mainstream finance industry, with its absurd "style" boxes, has difficulty pigeon holing him.

Mid-cap value? Large-cap growth? Heebner simply invests where he sees the best opportunities.

He's happy putting his Realty Fund in mining companies as well as mere real estate investment trusts. No wonder it's up a stunning 34% so far this year, while the real estate market has slumped.

Regular readers of this column will also spot many of the other characteristics of a really good mutual fund manager. Such as: Heebner has been around for decades (he's 66). He's seen it all. And he owns his own fund company, so he doesn't have to answer to some office bureaucrat.

Heebner is one of those fund managers that the "index" crowd likes to tell you don't really exist. They argue there's no point trying to beat the market over the long term. Or trying to "time" it so you get in or out of specific stocks at the right moment.

Sure, you can't always be right. Heebner made some wrong bets in the late nineties and fell behind the curve.

But he's been right a lot more than he's been wrong, and it shows.

Over the past 10 years, an index fund tracking the

Standard & Poor's 500

has turned $10,000 into about $19,900.

Heebner's CGM Realty Fund: $63,000.

As for his Focus Fund? Try $83,100. And counting.

In keeping with TSC's editorial policy, Brett Arends doesn't own or short individual stocks. He also doesn't invest in hedge funds or other private investment partnerships. Arends takes a critical look inside mutual funds and the personal finance industry in a twice-weekly column that ranges from investment advice for the general reader to the industry's latest scoop. Prior to joining TheStreet.com in 2006, he worked for more than two years at the Boston Herald, where he revived the paper's well-known 'On State Street' finance column and was part of a team that won two SABEW awards in 2005. He had previously written for the Daily Telegraph and Daily Mail newspapers in London, the magazine Private Eye, and for Global Agenda, the official magazine of the World Economic Summit in Davos, Switzerland. Arends has also written a book on sports 'futures' betting.