Whatever your dream, MercadoLibre Brazil is ready to sell you the bits and pieces you need to make it happen. Source: www.mercadolivre.com.br.

What: Shares of Latin American online retailer MercadoLibre (NASDAQ:MELI) fell 17.3% in September, according to S&P Capital I.Q. data, marking the company's fourth straight month of decline. 

So what: The current fiscal year is causing no small amount of consternation for MercadoLibre shareholders. Revenues have increased 22% through the first two quarters of the year, and the company's main economic engine, its "Marketplace" business, saw listings expand 59% year over year last quarter. Yet earnings are denominated in U.S. dollars, and this is turning out to be a major factor behind MercadoLibre's 26% stock decline year to date.

The company's business model is aimed at capturing e-commerce market share in the largest Latin American economies. The following is a geographical breakdown of MercadoLibre's revenue through the first half of 2015:

Country2015 Revenue through 6/30/2015:% of Total Revenue
Brazil $141.40 46.7%
Argentina $104.30 34.5%
Venezuela $19.70 6.5%
Mexico $19.40 6.4%
Other Countries $17.70 5.9%
  $302.50 100%

Source: MercadoLibre SEC filings.

While many Latin American currencies have weakened considerably against the dollar in recent quarters, the currencies of Brazil, Argentina, and Venezuela have been especially vulnerable to depreciation. Thus, a $21.2 million profit in the first half of the year swung to a $2.4 million loss after the effects of currency translation.

Investors have also been cautious on MercadoLibre shares this fall after Amazon.com announced an expansion in Mexico. Adding to the presence of its Mexican Kindle site, on June 30 the Internet retail juggernaut launched "Amazon.com.mx," a Spanish-language version of the Amazon.com site. In its press release, Amazon boasted that the millions of unique items offered for sale made the new site the "most comprehensive retail selection available to customers in Mexico." 

While MercadoLibre is the dominant e-commerce retailer in Latin America and will likely remain so for a long while, Amazon's entry into Mexico nonetheless will affect the company's Mexican revenue. Given the very recent launch, it may be a few quarters before management and investors alike can assess the impact of Amazon's incursion.

Now what: MercadoLibre's strategy of expanding in the largest Latin American economies will serve it well over the long term. But in a period of relative dollar strength, earnings will simply be less valuable to shareholders. Even so, as a long-term portfolio holding, the company remains a compelling global retail play. 

Asit Sharma has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Amazon.com and MercadoLibre. 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.