Every month, I do my level best to help the world invest better by publicly calling out the company that I'll be buying to add to my Roth IRA. In late December, I introduced  five companies I was considering as my stock pick for the month.

Today, I'm going to tell you about the company I'm picking, the reasons why, and offer access to a special premium report detailing the company in greater depth at the end of the article.

Let's review the choices that didn't make the cut
I'm a big fan of Apple (AAPL 0.68%)-- in  fact, the stock was my pick  last month -- and it accounts for roughly 8% of my real-life holdings. But at the time being, I want to leave that allocation where it is. I've already voiced in the past that I'm keeping a watchful and wary eye on the post-Jobs era at Apple.

Textainer (TGH), my pick as this year's top dividend stock for 2013, also didn't make the cut. Though I think the company has a definite competitive advantage with its worldwide list of clients and excellent logistical team, it's not quite the type of innovative company I like putting retirement money behind.

And then we have Intuitive Surgical (ISRG 2.01%) and National Oilwell Varco (NOV 1.34%). Both of these companies have risen significantly -- 4.7% and 8.9%, respectively -- since I called them out as candidates. That's not to say they aren't still buys; it's just to say that they aren't wildly underpriced.

Sounding like a broken record
As a writer, it's good to come up with new material for readers to digest. That's generally a good rule of thumb, and a reason why I thought long and hard before picking Baidu (BIDU 1.31%) as my stock to buy for January.

I've already made it a Core stock in "The World's Greatest Growth Portfolio, " and dubbed it as the top stock to buy in 2013. Who wants to hear me give the same spiel again?

After careful consideration, Fools, I was hoping you would. Now, it's never a good idea to load up too much on one stock all at once, and it's also never a good idea to fall in love with a stock. But if you can take a sober-eyed view of the situation and deem something as a solid buy for a couple of months in a row, then it's probably worth following legendary investor Peter Lynch's advice: "The best stock to buy may be the one you already own."

The story
For those not familiar with Baidu, the company is responsible for running China's largest search engine -- thus its moniker as "China's Google." Over the past five years, revenue has grown by 63% per year and earnings per share by 75% per year .

Those are big numbers, so you'd think that they company would be trading for a pretty high premium. But that's not the case, as it's now trading hands at just 17 times future earnings and has a PEG ratio of just 0.6.

There are a number of reasons for this: Some are worried about competition from Qihoo 360, some about accounting gimmicks, and some about the Chinese economy crash landing. Let's take them one at a time.

Qihoo is an upstart that's primarily focused on its safety and browser products. While the company could make a dent in Baidu's search market, Baidu already has an 80% market share in China, and is the most visited site in China. Google can't even claim that type of market share in America!

When it comes to accounting gimmicks, I'll readily admit that this is a real threat. There's nothing to suggest that Baidu is up to no good. It's simply that the SEC has announced it would be investigating the Chinese branch of the major U.S. auditors.

Finally, because I believe in buying stocks to hold for the long run-- meaning decades, not months -- I'm not too worried about a permanent and irreversible downturn in China. First and foremost, if Chinese residents continue to flock to the Internet, look at how much room there still is for growth. This shows Internet penetration rates in the U.S. and China. China would still need to double to reach the level where the U.S. is.

Source: World Bank. 

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