At the beginning of 2012, I decided the most honest and effective way to help the world invest better was to publicly show how I go about making decisions for a public portfolio aimed at growth companies. The intent is to hold each company for at least a year, and recalibrate only with each new year.

Since then, an investment of $50,000 would have grown to $69,650 -- or $5,200 more than if it had just been invested in an SPDR S&P 500 (NYSEMKT: SPY) ETF. Read on to see why the portfolio is doing so well, and how you can find out which of these 13 stocks are great buys right now.


CompanyAllocationJan. 1 BalanceCurrent BalanceChange
Baidu (NASDAQ: BIDU) 11.5% $115.00 $111.21 (3.3%)
Google 11.5% $115.00 $141.91 23.4% 11.5% $115.00 $123.97 7.8%
Whole Foods Market (NASDAQ: WFM) 11.5% $115.00 $131.68 14.5%

Tier One

CompanyAllocationJan. 1 BalanceCurrent BalanceChange
Starbucks 7.5% $75.25 $88.95 18.2%
Apple 7.5% $75.25 $63.89 (15.1%)
Intuitive Surgical (NASDAQ: ISRG) 7.5% $75.25 $76.88 1.9%
IPG Photonics (NASDAQ: IPGP) 7.5% $75.25 $66.90 (11.1%)

Tier Two

CompanyAllocationJan. 1 BalanceCurrent BalanceChange
3D Systems (NYSE: DDD) 5% $50.00 $68.35 36.7%
LinkedIn 5% $50.00 $73.55 47.1%
Stratasys  5% $50.00 $52.70 5.4%
Westport Innovations 5% $50.00 $56.80 13.6%
lululemon athletica 5% $50.00 $51.40 2.8%
 Jan. 1 BalanceCurrent BalanceChange
Year-to-Date $1,000.00 $1,107.97 10.8%
Returns Since Inception     39.3%

Source: YCharts. Because this portfolio is focused on capital appreciation, dividends are not accounted for in either individual stock or market returns.

Three big movers
Of the 13 stocks included in the portfolio, three made notable moves in May. The first of those companies was 3D Systems, which is up 29% from one month ago. Shares of all 3-D printing companies are especially volatile, as they come from an untested market that holds great potential for the future of manufacturing.

That's why positive earnings from 3D Systems at the beginning of May, combined with likewise news from fellow 3-D printer Stratasys, helped boost the entire industry throughout the month.

Second on the list of big movers was Chinese search engine Baidu, whose stock is up more than 14% over the past month. Though the company didn't come out with any big news itself, it was the earnings release from rival Qihoo 360 that caught Wall Street's eye. Though Qihoo continued to gain search market share -- now at 15% in China -- it was clear from weak advertising revenue that Baidu has a serious upper hand when it comes to pricing power with its advertisements.

Finally, Whole Foods gave shareholders lots of good news to snack on, as shares are up 17% over the past month. Previously, investors were worried that the company was lowering prices because other grocers were offering just as good a value on organic food.

But the latest earnings release showed that the lower prices weren't hurting Whole Foods. In fact, this makes it increasingly harder for other grocers to turn a profit on organic food, and as organic food becomes more affordable, the market of potential customers widens.

Two noteworthy events
Two other companies from this portfolio were in the headlines in May. First was Intuitive Surgical, which won a major court case. In the case, the plaintiff claimed that complications arising from a surgery performed with the daVinci robot were the company's fault not training doctors well enough. The jury disagreed, saying that the doctor himself was to blame.

Second big event was that shares of IPG Photonics fell after releasing earnings. Though the company grew earnings 15%, margin compression meant earnings per share were up only 10%. If you listened in on the conference call, however, the company said it was offering its lasers at lower price points to drive up adoption rates. Long-term, I think that's a very smart move for the company, as it's likely to win market share that will boost earnings in the years to come.

Best stocks to buy?
Every month, I pick out three stocks from this group and dub them as my "Best Buys" for the month. Keep your eyes opened, as I'll be revealing those three picks next week.

Fool contributor Brian Stoffel owns shares of Apple, Google,, LinkedIn, Starbucks, Baidu, Whole Foods Market, lululemon athletica, Intuitive Surgical, Westport Innovations, Stratasys, and IPG Photonics. The Motley Fool recommends 3D Systems,, Apple, Baidu, Google, Intuitive Surgical, IPG Photonics, LinkedIn, lululemon athletica, Starbucks, Stratasys, Westport Innovations, and Whole Foods Market; owns shares of 3D Systems,, Apple, Baidu, Google, Intuitive Surgical, IPG Photonics, LinkedIn, Starbucks, Stratasys, Westport Innovations, and Whole Foods Market; and has options on 3D Systems. Try any of our Foolish newsletter services free for 30 days. We Fools don't 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.