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What: Shares of truck and buss maker Navistar International Corp (NYSE:NAV) fell as much as 16.7% on Tuesday after being downgraded by an analyst. As of noon EDT, shares were still down 15.2%.

So what: Analysts at Stifel downgraded Navistar's shares from a hold rating to a sell rating. The company is coming off its first quarterly profit in some time, but analysts have been rapidly lowering their earnings estimates for fiscal 2016 and 2017 after management reduced industry demand guidance, which is making investors uneasy.  

Now what: Analyst upgrades or downgrades can often move a stock in the short term, but Foolish investors should always look at the long-term trends. Management has shown progress in its turnaround plan, and that showed with last quarter's profits. But the company also said it will be tough to be profitable for the full fiscal year because of a decline in expected Class 8 industry volume. While the short term may be challenging, don't overlook the progress Navistar has made. That sets the company up well for an industry recovery, but that may now be pushed out further than investors would like.  

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