Source: Philip Morris International.

Long-time shareholders in Philip Morris International (NYSE:PM) have been pleased with the performance they've seen in the six years since the tobacco giant became an independent company. But for more than a year, Philip Morris stock has seen its gains come to a halt, and the share price has even given back a bit of ground lately. Now investors want to know if the pullback is just a temporary phenomenon or a sign of greater challenges to come. Let's look at three of the key factors that could push Philip Morris stock lower in the future.

1. Dividend investors could lose confidence in Philip Morris.
Philip Morris International gave investors what should have been good news last week, raising its dividend by 6.4%, and thereby lifting its dividend yield to 4.8%. Yet shareholders shrugged off the announcement, seemingly disappointed that the tobacco giant wasn't able to raise its payout further.

Obviously, dividend investors are happy to get larger payouts. But the challenge that Philip Morris faces is that its earnings will likely drop this year, and that has longer-term investors nervous about where future dividend growth will come from. As you can see below, Philip Morris International's earnings payout ratio has been rising steadily since late 2011. That likely played a role in limiting the amount by which the company raised its dividend, which represented a slower growth pace than in past years.

PM Payout Ratio (TTM) Chart

PM Payout Ratio (TTM) data by YCharts.

With last week's dividend increase, Philip Morris International's earnings payout ratio rose above 80%. If the company can restore earnings growth, then dividends could follow suit and return to the growth rates that investors want. But investors will be nervous until that actually happens, and that nervousness could send shares downward.

2. Rising interest rates could ignite fears about Philip Morris debt levels and the sustainability of share repurchases.
Philip Morris International hasn't hesitated to take advantage of low interest rates to boost its long-term debt. Over the past five years, debt levels have more than doubled as the tobacco company has chosen a strategy of levering its balance sheet in a bid to keep its earnings-per-share growth intact.

PM Total Long Term Debt (Quarterly) Chart

PM Total Long Term Debt (Quarterly) data by YCharts.

At the same time, investors have enjoyed the benefits of massive share repurchases. In each of the past six years, Philip Morris has bought back at least $5 billion in stock, and combined with the ongoing cash flow needs from paying its dividend, the company has borrowed in order to return that much capital to shareholders. As long as interest rates remain low, that strategy could be short-term cash-flow positive, as the dividends on bought-back shares are higher than the financing costs on the debt. If rates rise, though, that dynamic could reverse itself and put further pressure on earnings -- while also making buybacks at higher levels look ill-advised in hindsight.

Source: Philip Morris International.

3. Recent litigation could damage Philip Morris International's reputation.
Last month, Philip Morris lost a court ruling, as an appellate court reversed an earlier decision to dismiss a lawsuit filed against the tobacco company alleging that it had defrauded the federal government by selling cigarettes to suppliers for stores that sell goods to members of the military and their families. The suit was brought under the False Claims Act, which enabled the president and CEO of a rival cigarette company to bring the suit on behalf of the government. Philip Morris argued that the executive lacked the necessary nonpublic information for the suit to be valid, but at least for now, Philip Morris will have to keep fighting.

Given the commercial nature of the lawsuit, even worst-case scenarios aren't likely to involve the sort of large damage awards that shareholders have always feared from health-related claims. But the negative publicity of allegations of taking advantage of service members definitely isn't something Philip Morris is looking forward to dealing with for the foreseeable future, and any further bad news could hold back the stock as well.

Philip Morris International is working hard to give shareholders everything it can. But if these concerns flare up into full-blown crisis situations, then the stock could see further pressure in the future.

Dan Caplinger has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.