Trefis members have created forecasts for two key drivers of PepsiCo's ( PEP) stock over the last week: the Pepsi U.S. CSD market share and its Diet Pepsi's U.S. CSD market share.

The forecasts suggest that Pepsi's U.S. CSD market share will trend higher than the Trefis forecast, while Diet Pepsi's U.S. CSD market share will be mostly in line with the Trefis forecast. These combined projections suggest very little upside to PepsiCo's stock.

However, higher-than-expected Pepsi's U.S. CSD market share may not bode well for Pepsi competitors The Coca-Cola Company (KO) and Dr Pepper Snapple Group ( DPS).

The Pepsi brand constitutes 5% of the $65 Trefis price estimate for PepsiCo's stock . By comparison, Diet Pepsi accounts for only 3%. The company derives majority of its value from Frito Lay (50%).

Below are charts showing recent estimates created by Trefis members for the two drivers.

The average of forecasts for Pepsi's U.S. CSD market share created by Trefis members indicated a projected increase from 10.4% in 2010 to 10.5 % by the end of the Trefis forecast period, compared to the baseline Trefis estimate of flat market share of 9.9% over the Trefis forecast period.

The member estimates imply less than 1% upside to the Trefis price estimate for PepsiCo's stock. In the past, Pepsi's US CSD Market Share has decreased from 11.2% in 2005 to 9.9% in 2009.

You can drag the forecast trend-line above to express your own view, and see the sensitivity of PepsiCo's stock to Pepsi's US CSD Market Share.

Our complete analysis for Pepsi's US CSD Market Share is here .

The average of forecasts for Diet Pepsi's U.S. CSD market share created by Trefis members indicated a projected increase from 5.6% in 2010 to 5.7 % by the end of the Trefis forecast period, compared to the baseline Trefis estimate of an increase from 5.6% in 2010 to 5.8% by the end of the Trefis forecast period.

The member estimates imply less than 1% downside to the Trefis price estimate for PepsiCo's stock. In the past, Diet Pepsi's U.S. CSD market share has decreased from 6% in 2005 to 5.6% in 2009.

You can drag the forecast trend-line above to express your own view, and see the sensitivity of PepsiCo's stock to Diet Pepsi's US CSD Market Share.

Our complete analysis for PepsiCo is here .
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