The stock market merry-go-round has been the ride that just won't end. Lately, though, Altria (NYSE: MO) has provided much delight for investors, outperforming the S&P 500 by more than 2-to-1 over the past year.

However, first-quarter results, while good, may signal that Altria may be coming back to earth in the short term.

Yes, the quarterly EPS of $0.44 was in-line with analysts' estimates. And the year-over-year EPS growth of 4.8% is nothing to sneeze at, especially since net revenue dropped by 2% and the company's investment in SABMiller (OTC BB: SBMRY.PK) delivered a net loss on quarterly results. Altria is definitely managing itself well, delivering a 3.9% reduction in cost of goods sold and a 7.6% increase in operating income for the quarter.

OK, so now for the bad news. Altria's cigarette volume was down 6.4% for the quarter, with a 5.7% decline in Marlboro volume and 13.5% drop in discount cigarette volume. For a declining industry such as tobacco, losing volume isn't a surprise, but giving up market share is a blow, and Altria lost market share all around this quarter. Overall cigarette market share was down by 1.2 points, with Marlboro giving up 0.5 points and discount cigarettes dropping by 0.4 points.

Compare those results with last quarter, when cigarette shipment volume was down by 7% but Marlboro market share was up by 0.6 points, and you can see there's a bit of concern for the future. Altria says that some of the decline was due to the timing of product launches, but I'll be interested to see if Marlboro can retain its top-notch status even with the economic uncertainty that we're facing.

Maybe more telling, though, the company stalled its one-year, $1 billion stock repurchase program and did not buy back any shares in the first quarter. This could mean that Altria's leadership team believes that the stock is overpriced (after all, the price is up more than 20% over the past year), or it could mean that the executive team is saving up for more rainy days to come. I'm thinking that it's the latter, with balance sheet cash up by $1.1 billion in the last three months.

Reynolds American (NYSE: RAI) reports its quarterly earnings tomorrow and Lorillard (NYSE: LO) delivers earnings early next week, so we'll see if they've picked up some of Altria's lost share. Altria's globe-trotting cousin Philip Morris International (NYSE: PM) also reports earnings tomorrow. If Marlboro's share dropped globally this quarter, then it could be a sign that folks aren't willing to pay extra for premium cigarettes in this economic environment.

Altria's dividends continue to grow and the stock price has definitely blossomed lately, so all is not lost for investors. However, I'd keep an eye on results (especially market share) before plunking down any more cash into Altria in the near term.

Fool contributor Colleen Paulson does not hold positions in any of the stocks mentioned in this article. SABMiller and Philip Morris International are Motley Fool Global Gains picks. The Fool owns shares of Altria and Philip Morris International. For more investing insight, you can always give the Fool's newsletters a try via the 30-day free trial. 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.