It's not too often that investors get the opportunity to play on major shifts in society, but it does happen from time to time. KinderCare in the late 1970s, cable TV and computers in the 1980s, and the Internet in the 1990s all gave investors the opportunity to invest in companies that were part of a larger shift in American society. Now, in the first decade of the 21st century, investors may once again have that opportunity.

The change in this case is the growing percentage of America's population that is Spanish-speaking and/or of Hispanic descent. With more than 14% of the nation of Hispanic descent, and a population growth rate nearly four times the national average, there is no doubt this is a major demographic change. As the hands-down leader in Spanish-language broadcasting, Univision (NYSE:UVN) is one of the more obvious ways to play this shift.

Results for the fourth quarter support the notion that Univision remains the runaway leader in its markets. Revenues and net income were both up in the low teens (including variable interest entities) and Univision's flagship channel increased its primetime viewership by 8% in an environment where major networks are happy to tread water.

Univision continues to crush would-be rivals like GE's (NYSE:GE) Telemundo network. Furthermore, management no longer considers other Spanish-language networks to be the network's prime competitors. Rather, Univision is now competing with the likes of Disney's (NYSE:DIS) ABC, GE's NBC, Viacom's CBS, and News Corp's (NYSE:NWS) Fox network.

To some extent, this viewpoint is valid. Other dedicated Spanish-language broadcasters like Telemundo and the emerging Azteca America (owned by Mexico's TV Azteca (NYSE:TZA) aren't major threats today.

What could be a major threat, though, is the expansion of existing major networks into Hispanic programming -- ventures like ESPN Deportes, MTV Latino, and a host of low-priced Spanish-language tiers offered by cable companies like Comcast (NASDAQ:CMCSA).

A secondary threat is the timing of the pickup in advertising expenditures. Although ad spending targeting the Hispanic market has grown considerably, it still lags behind English-language TV on a per-viewer basis. Though this should improve with time, investors considering Univision need to realize that the company's dominance (nearly 80% share) in its market does not always quickly translate into the lucrative revenue flow that would be seen by a similarly successful English-language broadcaster.

Nevertheless, Univision is producing considerable amounts of cash flow. Free cash flow (excluding a building purchase) for 2004 grew more than 30% to $357 million. Univision's management is also working to put some of that dinero into shareholders' pockets. Leveraging the company's strong cash flow generation and reasonable balance sheet, Univision will launch a $500 million share-buyback program in 2005.

As the vanguard of what may well prove to be a major change in American culture and society, Univision could be a powerful company in the years to come. Although the stock looks expensive by conventional measures, media companies rarely trade according to conventional measures. Compared with its peers, then, Univision's valuation looks a bit more reasonable, especially considering its cash flow growth and dominant position in a fast-growing market.

Although Univision will no doubt see some erosion in its market share as time goes on, Fools looking to invest in what could be a major trend of the decade should spend some time examining Univision.

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Fool contributor Stephen Simpson , CFA, has no ownership interest in any stocks mentioned, but he is a frequent viewer of Univision's Primer Impacto and Sabado Gigante programs.