Dunkin' Brands (Nasdaq: DNKN) must be wondering what's going on when the company that underwrote its initial public offering a mere two months ago is yelling, "Get out!" at the top of its lungs.

Investors must be wondering, too. The share price, which had risen 42% since the IPO, started the day by falling almost 5% on the "sell" rating.

Goldman Sachs (NYSE: GS), the fickle underwriter, opened the day with that downer rating, noting that Dunkin's core domestic business is "highly macro-sensitive against an uncertain economic backdrop." So what's changed? I don't remember the domestic macro-economic picture looking all that great two months ago, either, do you?

Three of Dunkin's other underwriters haven't helped much, either. Barclays (NYSE: BCS), Wells Fargo (NYSE: WFC), and Bank of America (NYSE: BAC) gave tepid "neutral" or "equal weight" scores to the company.

But valuation ...
Goldman said it liked Dunkin's global potential, as did Barclays. But both said, in essence, that the stock is overpriced compared to its competitors such as McDonald's (NYSE: MCD) and Starbucks (Nasdaq: SBUX).

Company

P/E (trailing)

Dunkin' Brands 38
McDonald's 18
Starbucks 28

... is in the eye of the beholder
But wait -- other Dunkin' underwriters have taken a totally different view of the company. JPMorgan Chase, the top underwriter of Dunkin's IPO, even gave it an "overweight" rating, saying "low-risk growth should sustain [its] premium multiple."

Dunkin's ambitious plan had been to increase the number of its stores to 15,000 over the next 20 years. However, Goldman estimates that the company would only be able to sustain another 3,200 stores, for a total of 10,000. By way of comparison, McDonald's has 14,000 domestic stores, and Starbucks has 10,900.

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Fool contributor Dan Radovsky has no financial interest in any of the mentioned companies. The Motley Fool owns shares of Starbucks and Bank of America. The Fool owns shares of and has created a ratio put spread position on Wells Fargo. Motley Fool newsletter services have recommended buying shares of Starbucks and McDonald's. 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.