Practically everybody knows a stockbroker who's good -- maybe even great -- at picking winners. But who's the hottest stock picker around? I can't say with absolute certainty, but you would be hard-pressed to find anybody in the past few years who even comes close to Ignatius "Igo" (pronounced ego) Teichberg. The institutional research chief of the brokerage firm of Gruntal & Co. has been phenomenal, especially in selecting shares of companies that eventually are taken over. And it's hardly news to anybody that the takeover game has been the single biggest money-making craze on Wall Street the past couple of years.

In case you don't know how good he is at his trade, the non-stop-talking Teichberg would be more than pleased to tell you -- not once, but at least a dozen times during any five-minute conversation. His nickname fits him well.

I first caught up with Teichberg in September 1977. I had heard about his stock-picking abilities, and I interviewed him. In the course of that get-together, he mentioned 13 stocks that he liked. They went through the roof. As of last Monday, his selections were up an average 103 percent (only one was down); in the same period, the Dow Jones Industrials fell slightly. Of the group, 7 were pinpointed as takeover candidates. Subsequently, 4 of them -- Washington Steel, Flying Diamond, Beech Aircraft and Reserve Oil & Gas -- either were acquired or are involved in acquisition negotiations.

His most recent winner in this respect is Beech, which was 20 at the time of the 1977 interview. Last week, the company announced it was holding merger talks with Raytheon; the news was known long before the official announcement, and Beech shares are now selling at around 39.

Considering his remarkable performance, I decided to revisit Igo. Even if he had any humility the last time I interviewed him -- and I'm not sure that he did -- it was non-existent this time.

"Talk to the people at Chemical; they'll tell you how great I am," he shouted. "I'm unbelievable; the institutions are now following Igofs . . . "

I tried asking a few questions moments after we met, but to no avail. Hovering over me and pushing a bunch of papers in front of my face, one of which slightly entered my mouth, Igo howled: "Look, just look at my recommendations from last June. Here, Canadian Superior at 111; it's now 140. And Dome Petroleum, it was 34; it's now 46 3/4." I tried again to say something, but no luck. "And look, Ranger Oil. Last June it was 21; now it's 34. I want to give you more; let me give you more: Hudson Bay, it was 54 1/8; today it's 76."

Totally exasperated, I got up, explained I had to make a call and left the conference room for a few minutes.

When I returned, I didn't give him a chance to say a word and immediately asked: "What do you think of the market.

"I really don't care what the market does," he replied. "I'm buying stocks, not the market."

But why is the market acting so well in the face of such bad news (such as booming interest rates and spiraling inflation)? "The market's going up -- and I see a tremendous up -- because people have concluded that Carter is not going to be re-elected . . . and that's a plus," said Igo. "Carter has no leadership; he's indecisive; he doesn't know how to talk to the Arabs, what to do about energy, and he can't stand up to the Russians. So the idea that we'll get someone new -- anybody -- has got to be good for the market."

"And besides, stocks are undervalued; they're the cheapest buys around. Everything's gone up: real estate, gold, commodities, but not the stock market. There's a lot of stocks around that are dirt cheap."

The obvious next question: What does Igo like? In fact, I asked him if he'd make a list of his favorite securities. He obliged. And of the 20 -- which Igo says have the potential to rise between 70 percent and 90 percent over the next 12 months -- 10 are regarded as takeover candidates.

Igo is convinced that the takeover craze will continue. "Because of inflation, the price of expansion (such as building new plants and adding new equipment) is getting more and more expensive," Igo observed. "Everybody knows it; they know it's cheaper to buy than to build . . . and that's why you're going to see more and more deals. And don't forget about the foreigners holding cheap U.S. dollars. They're going to buy more and more. Look at the Howard Johnson deal. Imperial Tobacco is paying $28 a share to buy the company (a price that some investment bankers regard as absurdly high). If anyone here had gone for the company, they would have paid maybe $22 to $23 a share. You can see how hungry foreigners are for our assets . . . "

Of his 10 corporate takeover candidates, Igo's five favorites are Integon Corp., MGIC Investment, Mohawk Data Sciences, Texas International Oil and Wylain.

I don't know about you, but I'm the impressionable type. And anybody with a record like Igo's is bound to attract eager investors who might be quick to snap up some of his stock selections. I'm even tempted myself. But it should be duly noted that Igo also has had his share of losers (like Brunswick, Houston Oil & Minerals and Sambo's Restaurants). And no Wall Streeter I've ever met stayed hot forever.

The message is clear; Caveat emptor.