The "Mad Bomber" of Wall Street strikes again!That would be Ken Heebner, legendary, if somewhat eccentric, manager of ( CGMRX) CGM Realty (CGMRX) and ( CGMFX) 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), fertilizer companies Mosaic ( MOS) and Potash Corp. ( POT) of Saskatchewan, and big power infrastructure companies Fluor ( FLR), Foster Wheeler ( FWLT), McDermott ( MDR) and Cummins ( CMI). 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) and Companhia Vale do Rio Doce ( RIO) and oil company Petroleo Brasileiro ( PBR).