Satya Nadella speaking at the 2016 World Economic Forum in Davos, Switzerland. David A. Grogan | CNBC

In late 2014, when software developer Hortonworks was getting ready to go public, the company was not in the healthiest position. Almost one-quarter of its revenue came from a single company: Microsoft. While that was an improvement from the prior year, when a staggering 55 percent of sales came from Microsoft, it was still a bright red flag for investors, who were concerned about whether Hortonworks was diversified enough to flourish as an independent company. From its $16 IPO price in December 2014, the stock lost more than half its value over the next 22 months to a low of $6.42 in October 2016. Hortonworks had a good reason for its Microsoft collaboration, which started in 2011, the same year the fledgling company spun out of Yahoo. As a start-up with a package of open source software for running big data projects, Hortonworks' early integrations with Microsoft's Windows Server operating system and Azure public cloud allowed the company to pick up new business that it couldn't have attracted on its own. "It put us on the map," said Mike Volpi, a Hortonworks board member and a partner at Index Ventures, which backed Hortonworks in 2011. "It gave us access to a lot of important customers. It was definitely material." Microsoft CEO Satya Nadella, who was involved in the Hortonworks deal when he was running the cloud division, said at an event in July that "Microsoft has always been a partner-led company." Today, five companies derive at least 10 percent of their revenue from Microsoft, according to FactSet, but Hortonworks isn't one of them. As of 2016, its reliance on Microsoft was down to 6 percent. Hortonworks now has more than 1,000 customers with active support subscriptions, up from 332 at the end of 2014.

Companies most dependent on Microsoft Company Industry Microsoft reliance Market cap Perion ad-tech 49% $79 mln Applied Opto telecom equipment 18% $754 mln EA games 17% $32.4 bln Take-Two games 10% $12.3 bln AMD semiconductors 10% $10 bln Activision Blizzard games < 10% $48.2 bln Hortonworks IT services 6% $1.4 bln

Investors who stuck around have been rewarded. The stock has more than tripled from its low point and was trading at $20.54 as of midday Tuesday. Diversifying beyond Microsoft has only been a part of the turnaround. Volpi said that Wall Street, which had been critical of high sales and marketing costs at Hortonworks, has now seen that spending pay off in terms of continued growth. In the latest quarter, Hortonworks generated 45 percent revenue growth from a year earlier, while its operating expenses fell slightly. The Hortonworks story resonates across technology and beyond. The five most valuable companies in the world are all U.S. tech companies, and an increasing number of businesses are reliant on those platforms for distribution and revenue. It's a double-edged sword. As quickly and efficiently as Microsoft, Apple, Google, Amazon and Facebook can help smaller players get traction, they can just as readily take it away by launching a competitive product, changing pricing or altering their strategy.

'It was concerning'

Abhey Lamba, an analyst at Mizuho who has followed Hortonworks for years, said the issue of Microsoft concentration was a real one in the company's early days. "It was concerning because at that time you're reliant on Microsoft quite deeply," said Lamba, who now has a hold rating on Hortonworks. Accounting standards require that public companies in the U.S. disclose any customer that accounts for 10 percent or more of revenue. Two companies that currently count Microsoft as a 10 percent customer -- Electronic Arts and Take-Two Interactive Software -- make games for Microsoft's Xbox game console. For them, Microsoft is both a distributor and a competitor, because the software giant acquired the developer behind "Minecraft" and makes its own games like "Forza Motorsport 6" and "Halo 5: Guardians." Gaming revenue, which includes console and subscription sales, came out to less than 8 percent of Microsoft's total revenue for the quarter that ended in September.

Two hardware makers have an outsized dependence on Microsoft. Chipmaker AMD received more than 10 percent of its revenue from Microsoft in 2016 by selling processors embedded in Xbox consoles and Azure servers. And then there's Applied Optoelectronics, an obscure Texas company specializing in fiber-optic networking equipment for cable TV and data centers. Applied has seen its Microsoft business swell from 3.6 percent in 2014 to 12 percent in 2015 and 18 percent in 2016. Its technology is used to ensure that data can move quickly around data centers, which explains why Microsoft and Amazon together accounted for 73 percent of Applied's revenue last year. Amazon, through its cloud-computing division, and Microsoft are the two top cloud infrastructure providers, and both are investing heavily in equipment to handle the surge of data moving to the public cloud. Microsoft's capital expenses topped $10 billion in the latest fiscal year. Applied is picking up substantial business as a low-cost player in a market that includes the likes of Finisar, Lumentum and Oclaro. The stock has surged 65 percent this year. But things got rocky in October. The company issued a statement with preliminary results for the third quarter and investors hit the exits, sending the shares down 12 percent. The stock is more than 50 percent off its high from August.