Last December, over 100 stocks were featured in our Top Picks for 2007 report. Now, at mid-year, we turn to the 20 advisors whose picks showed the strongest gains to get an update on their previous picks, as well as a new favorite stock for the second half of the year.

Nick Vardy, editor of the Global Stock Investor, chose América Móvil (NYSE: AMX) as his favorite stock for 2007, which rose 38% as of 6/1/07. Here is his original recommendation for AMX and his current opinion on the stock.

For his new favorite idea for the second half of 2007, the advisor looks to Millicom International Cellular (NASDAQ: MICC), which he calls, the "Indiana Jones" of the global cell phone industry. He explains, "Luxembourg-based Millicom is one of a handful of global players that are profiting by expanding in cell phone markets where others fear to tread.

"Its strategy has been unique and daring. While the Vodafones and América Móvils of the world slug it out in big cell phone telecommunications markets such as Brazil and India, Millicom has cobbled together a patchwork empire that consists of 16 countries in Central America, South America, Africa, and South and Southeast Asia.

"In total, Millicom's cellular operations are licensed to serve a combined population of approximately 278 million people -- roughly the population of the United States. Millicom has focused on offering prepaid cell phone services in countries where landlines are inadequate.

"Although most of Millicom's sales growth occurs in traditional Latin American markets, more than half of Millicom's customers are in Africa and Asia. And that's where much of Millicom's future growth lies. Given the relatively low cell penetration rates, Africa is the fastest-growing region of the world for cell phone use.

"A key difference in emerging markets is that most cell phone users buy prepaid plans. Millicom has learned how to sell this service. What sets Millicom apart from its competitors is that it lets customers buy minutes in very small denominations -- even seconds. This approach enables even the poorest buyers to get some airtime.

"It's no surprise that Millicom's extraordinary growth has made it a takeover target. Millicom put itself on the auction block in January 2006 by hiring investment bank Morgan Stanley to seek a buyer. The move has made holding Millicom stock a bit of a roller-coaster ride.

"Meanwhile, insiders own more than 39% of Millicom stock, so when you invest in Millicom, its management does, too. Anyone doubting Millicom's ability to make money in its challenging markets need only look at its recent blow-out financial results. The company's revenues almost doubled in fourth quarter 2006, compared with the same period of 2005.

"Analysts polled by Thomson Financial expect earnings this year to double to $3.54 a share. That puts the stock on a P/E of just over 23 -- a bargain based on almost triple-digit percentage growth rates. Millicom hit a record high of $85.95 on May 7. From a technical point of view, the stock may be poised for a breakout on the upside."

See all 20 stocks the advisors picked for the second half of 2007.