They targeted the energy drink market after Red Bull -- popularized by marketing executive Dietrich Mateschitz, who began selling the drink in his home country of Austria in 1987 -- rapidly expanded in Europe and plunged into the U.S. market.
Red Bull, which has made Mateschitz a billionaire, is now sold in 130 countries, and the company says it has no fear of Monster and the other new entrants.
Their arrival "really just validates the category," and Red Bull "is committed to staying ahead of the curve," said Patrice Radden, a spokeswoman at Red Bull's North American headquarters in Santa Monica.
For now, Sacks and Schlosberg are enjoying the financial rush from Monster. The pair lead a group of Hansen insiders who together own 25.6% of Hansen's stock, according to the most recent proxy, a stake now worth nearly $400 million.
But they're also cautious about the future, and Hansen doesn't provide earnings guidance to Wall Street.
"The future is uncertain," Sacks told analysts this week. "We don't know where it is all going to go."
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Jostling for jolt
Hansen's performance has soared on the strength of Monster, its entry in the rapidly growing market for energy drinks.
Top-selling energy drinks and market share of U.S. retail sales in dollars on Aug. 31
Red Bull*: 46%
SoBe No Fear: 6.6%
SoBe Adrenalin Rush: 5.2%
*Data include sales of diet drinks.
Sources: Beverage Digest, Bloomberg News