Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

Will Washington ever come to an agreement? That's what investors were asking in a glum day for the markets, as the government's strife helped push down stocks across the markets. The S&P 500 (^GSPC -0.00%) pulled off a major turnaround to end the day, but it wasn't enough to keep it out of the red: The index ended up losing 0.1% after falling into much deeper lows earlier.

This week's shutdown has dominated the press, but it's the looming debt ceiling raise debate that has analysts and economists worried. If Washington can't even reopen the government -- a matter that fortunately won't likely have much of an economic impact -- the debt ceiling battle could be a monumental impasse. Investors have been spooked by the prospect of the government missing its bill payments, which could happen by the end of October if the debt ceiling isn't hiked, according to the Congressional Budget Office.

Private sector job growth also didn't impress today, with 166,000 new  jobs added in September, according to ADP. The number missed economist projections of 180,000 new jobs. Still, even with the downbeat data and investors cautiously circling Washington's political fallout, several of the S&P 500's stocks pulled off impressive gains for shareholders.

North America's second-largest fertilizer producer, Mosaic (MOS -1.04%), notched gains of nearly 3.7% today. While there wasn't much news out of the company today, Mosaic's phosphate-exporting joint venture with PotashCorp, PhosChem, was disbanded, according to an announcement from the company. Mosaic supplied 93% of PhosChem's export volume, but the joint venture has meant less and less for the company recently as it established phosphate ventures with two Saudi Arabian firms to export product to India. The stock's been due for a bump for some time considering that Mosaic's shares have fallen 23.5% year to date. But investors should take heed: Mosaic slashed its potash and phosphate sales outlook for the quarter back in September, and more shareholder pain could be on the way this earnings season with the fertilizer market's global dip.

Software and services design firm Autodesk (ADSK -0.31%) delighted shareholders as well with a 5.1% gain on the day. The company announced today that annual billings will rise an average of 12% per year through fiscal 2018. Autodesk further expects a 50% jump in its subscription base through that time, a number that should help the company ward off declining sales. The firm's revenue has declined sequentially in each of the past two quarters, although Autodesk's stock has jumped more than 20% in the past three months alone.

However, neither Autodesk nor Mosaic could lmatch the gains posted today by Tenet Healthcare (THC -0.99%), which saw its stock jump 6.1%. Tenet's looking to capitalize on Obamacare, and CEO Trevor Fetter said today the company plans to double its presence in Texas. Tenet is targeting large, populous states such as Texas, California, and Florida with high numbers of uninsured residents who could flock to new health care exchanges. Tenet also completed its purchase of Vanguard Health Systems yesterday, a move that also will help the company's reach as it looks to expand to more patients, particularly now that millions of Americans are expected to pick up health insurance and reduce hospital costs of treating uninsured patients. Some major insurance giants have shied away from Obamacare's exchanges in fear of high prices, but for Tenet they offer a major opportunity to make a big impact in a new market

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