FORTUNE — For most of the 12 years since the dot-com bubble burst, Cisco was a true tech bellwether. Its stock performance has largely tracked the Nasdaq. Its switches and routers composed the nervous system of an increasingly connected world, and so its orders became an early warning system of sudden shifts in the broader economy. Cisco won Wall Street’s respect by regularly sharing its views on the macroeconomy in its earnings conference calls.

In January 2008, for example, Cisco (
CSCO
) noticed a slowdown in orders coming from automakers and financial institutions — a warning of the financial crisis and recession that was to follow. In March 2009, in the nadir of the Great Recession, Cisco again forecast a bottom, reporting that its customers were seeing “stabilization” as the worst was passing.

By 2009, Cisco wasn’t quite the Silicon Valley luminary it was in the late 1990s, but it was still considered the Internet’s backbone, the biggest seller of switches and routers. A year later, Cisco began to face tough problems. After reaching $27 a share in April 2010, Cisco began to slump.

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More than that, Cisco stopped tracking the Nasdaq. It’s lost 21% of its value since the spring of 2010, while the Nasdaq Composite Index has gained 59%. Cisco went from bellwether to laggard, hurt by competition on the low end of its market, the rise in software-driven networks and the desire of giants like Apple (AAPL), Google (GOOG) and Facebook (FB) to build their own data centers.

Cisco’s efforts over the years to diversify into set-top boxes, software, and other markets have had mixed results. The company cut 8,000 jobs in recent years, helping to push its stock back above $26 a share in August of this year. Shortly after, the stock declined as Cisco warned investors of slower revenue growth. Cisco said then it would cut another 4,000 jobs, prompting concerns of how many cuts were needed for Cisco to turn itself around.

Last week, the news became even more dire. The company said it expects revenue to decline 9% in the current quarter and forecast profit at 46 cents a share, or 6 cents below the Street’s consensus. Since then, Cisco has lost another 11%, falling to $21 a share. That puts Cisco’s stock exactly where it traded a decade ago, in mid-November 2003.

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How much of the recent declines are caused by Cisco’s internal issues vs. the macroeconomic factors the company has long been able to predict? Goldman Sachs figures it breaks down to two parts Cisco problems to one part global economy. Longer term, Cisco can still turn things around by buying its way into growing markets. What’s more worrisome is the suggestion of new economic headwinds: Does Cisco see another storm coming?

In last week’s conference call, CEO John Chambers pointed to a sudden slowdown in orders in late September. The impact of the government shutdown was muted, he said, (revenue from government customers declined only 1%). Rather, the decline was coming from a number of emerging economies, where orders suddenly dropped off in October.

In the most recent quarter, Chambers said, “Our top five emerging markets declined 21%, with Brazil down 25%, Mexico down 18%, India down 18%, China down 18%, and Russia down 30%.” Orders from North America and Europe rose slightly. Pubic sector revenue did well despite the U.S. government shutdown, but orders from service providers fell 13%.

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Last month, IBM (IBM) reported a 9% drop in revenue from emerging markets, driven largely by China’s shift in economic policies. Cisco’s earnings forecast spurred discussion that China is retaliating against U.S. policies limiting the import of telecom equipment from Huawei, as well as the fallout from the NSA leaks. But Cisco’s problems went well beyond China.

At its annual shareholder meeting Tuesday, Chambers elaborated further. “I believe that we are in a period of much slower economic growth than we should be in for a whole bunch of different reasons,” he said. In terms of emerging economies, “they are going to hit pretty hard … Our numbers would indicate it might get tougher before it gets better.”

Chambers comments Tuesday coincided with news that the OECD was cutting its global growth forecasts for this year and next, citing an imminent slowdown in emerging markets like India and Brazil.

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During the 1998 financial crisis in Asia, Cisco increased its investment in the region, strengthening its market share in several countries when they recovered. It’s not clear the company will be so aggressive this time. “We’ve decided that given the uncertainty of the market, we want to keep a certain amount of our powder dry in terms of opportunities,” Chambers said in answer to a shareholder question Tuesday.

Instead, Cisco will be applying its cash to shore up its own stock. Last quarter, the company bought $2 billion of its own stock. In the same quarter a year earlier, Cisco bought $253 million, or one-eighth as much. The company also said last week it would increase its repurchase program by $15 billion, giving it a total of $31 billion to spend on its flagging stock in the future.

Cisco may be as prescient as ever about predicting shifts in the global economy, but as long as it’s stuck in the middle of a long and difficult turnaround it will have a hard time taking advantage of them.