The results are in. The four major US \ tobacco companies have all reported their fiscal third quarter results, and a worrying trend has started to emerge.

Philip Morris International (PM -0.65%) is the only international tobacco company listed in the S&P 500. Reynolds American (RAI), Lorillard (LO.DL) and Altria (MO -0.92%) are all, for the most part, domestic tobacco companies. Yet despite its international diversification, Philip Morris reported the worst set of results in the group.

Declining volumes
What concerned me most about Philip Morris' fiscal third quarter results was the staggering decline in the number of cigarettes shipped by the company. In particular, during the third quarter the company noted a 5.7% decline in cigarette shipment volume.

Actually, Reynolds was the only other company in the group that reported a decline in the number of cigarettes shipped, a decrease of 4.3% for the period. In comparison, both Altria and Lorillard reported increases in the number of cigarettes shipped. Specifically, Altria reported a gain of 1.3%, and Lorillard reported a gain of 3.5%.

Furthermore, what's really interesting is the fact that sales of the infamous Marlboro brand, the cornerstone of Philip Morris' tobacco portfolio, declined 2.5% during the third quarter. However, within the United States' domestic market sales of Marlboro cigarettes, sold by Philip Morris USA, which is owned by Altria, actually expanded 1.5%.

Foreign exchange
Having said all of that, one of the most damaging effects on Philip Morris' fiscal third quarter results was the strong US dollar. While the dollar has now weakened from its highs, the company has still suffered. For example, Philip Morris noted that unfavorable currency effects cost the company $0.23 per share during the first nine months of this year.

To put this in perspective, if the company had not suffered these negative effects Philip Morris would have earned $4.25 for the first nine months of the year, up 8.4% year-over-year, or YoY. However, after the negative effects of currency the company only earned $4.02 per share, up only 2.6% YoY.

Lorillard, Reynolds, and Altria have almost no foreign exchange exposure.

Declining volumes and the impact of foreign exchange are the two main factors hampering Philip Morris' growth. Indeed, Philip Morris already cut its full year earnings forecasts twice this year and now expects to earn between $5.35 and $5.40 for the full year. This is down from the $5.80 per share many analysts predicted at the beginning of the year . Even at the high end of the range, Philip Morris' YoY earnings growth will only be 4.4%.

Meanwhile, Reynolds is guiding for full-year earnings growth of 7% to 10%. In addition, the company noted that reported GAAP income for the first nine months of this year is up by just over 30% YoY.

Moreover, Altria has also kept its full-year guidance steady throughout the year. The company predicts earnings-per-share growth of 7% to 9% for the full year. Additionally, Altria reported that nine-month reported diluted earnings per share were up 34% from the comparable period.

What's more, Lorillard reported nine-month earnings-per-share growth of 18% on a GAAP basis.

Wide offering
You cannot deny that Philip Morris has a wide product offering. Indeed, the company owns ten of the best-selling cigarette brands in the world, as well as numerous local and value brands. Furthermore, the company has a joint venture with Swedish Match AB to commercialize smokeless tobacco products outside of Scandinavia and the United States.

However, these products are all smoking related. In comparison, Philip Morris' parent Altria has one of the most diversified business models in the global tobacco sector, apart from maybe Japan Tobacco. Altria's portfolio contains both cigarettes and smokeless tobacco products, but the company also has interests in vineyards for the production and sale of wine. What's more, the company also holds a significant share of SABMiller, with two seats on the board of directors.

That said, during the first nine months of the year only 2.2% of the company's revenues came from wine production, and the company has yet to make a significant profit from its holding in SAB. Still, some diversification is better than none, and it will start to play a greater role in the company's operations going forward as cigarette consumption declines.

Foolish summary
Traditionally, Philip Morris has been considered the tobacco stock of choice for investors looking for international diversification and earnings growth. However, these recent results do raise some concerns, and it is possible that the company could be losing out to its domestic peers, which appear to be growing much faster.