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.

Good morning, fellow Foolish investors! Let's take a look at four health-care stocks -- Teva Pharmaceutical (TEVA -1.23%), AMAG Pharmaceuticals (AMAG), AstraZeneca (AZN 2.65%), and Nektar Therapeutics (NKTR 3.24%) -- which could all loom large in headlines this morning.

Teva tries to delay Copaxone's patent expiration
First and foremost, Teva has asked the Supreme Court to review a July 2013 ruling that invalidated several crucial patents for Copaxone, its blockbuster multiple sclerosis (MS) drug, which accounts for roughly a fifth of its revenue.

This is clearly a last-ditch effort by Teva to block generic competition for the drug, which will lose patent protection in the U.S. in May 2014. Mylan (NASDAQ: MYL) and Momenta Pharmaceuticals (NASDAQ: MNTA) intend to release generic Copaxone the moment Teva's patent expires.

If generics are allowed into the market, Teva forecasts fiscal 2014 earnings of $4.20 to $4.50 per share on revenue of $19.3 billion to $20.3 billion. Analysts polled by Bloomberg had expected Teva to earn $4.92 per share on revenue of $19.9 billion. Every month that generic Copaxone is delayed could contribute $78 million in sales and $0.08 to its earnings per share.

However, generic Copaxone isn't Teva's only problem. The injected drug already faces stiff competition from a new generation of orally administered MS drugs, such as Biogen's (NASDAQ: BIIB) Tecfidera and Novartis' (NYSE: NVS) Gilenya -- which are both expected to achieve blockbuster status over the next few years.

The FDA dashes AMAG's hopes for an IDA approval for Feraheme
AMAG Pharmaceuticals could dive this morning after the company received a complete response letter from the Food and Drug Administration regarding its supplemental new drug application (sNDA) to expand Feraheme's approved indication to include all adult iron deficiency anemia (IDA) patients who have failed or cannot tolerate oral iron treatments.

Feraheme, which is injected, is currently approved for chronic kidney disease (CKD). The FDA did not believe that AMAG had provided sufficient information to demonstrate that the drug was safe to treat IDA patients as well.

More specifically, the FDA requested that AMAG test its IDA patient population for serious hypersensitivity, allergic reactions, cardiovascular problems, and death. It also suggested the evaluation of alternative dosing methods for the drug.

This means that Feraheme, which generated $19.3 million in sales last quarter for AMAG, still has a long way to go to hit even more conservative peak annual sales estimates of $250 million. The drug could also suffer from stiff competition from Rockwell Medical's (NASDAQ: RMTI) Triferic, a similar treatment that has shown promise in phase 3 trials.

AstraZeneca's Xigduo wins European approval
Meanwhile, AstraZeneca's type 2 diabetes drug Xigduo was approved in the EU today. Xigduo is a combination drug that combines its SGLT2 inhibitor Forxiga with metformin, a standard diabetes drug that suppresses glucose production in the liver.

Forxiga was also recently approved in the U.S. (as Farxiga), making it the second FDA-approved SGLT2 inhibitor after Johnson & Johnson's Invokana. SGLT2 inhibitors are a new class of drugs that help type 2 diabetics excrete more glucose through the urine.

Investors should also remember that AstraZeneca bought out Bristol-Myers Squibb's (NYSE: BMY) stake in its diabetes joint venture for up to $4.1 billion in December 2013, which means it will have full marketing rights to their previously shared diabetes portfolio, which includes Onglyza, Forxiga, and Xigduo.

Forxiga is expected to eventually generate peak sales of up to $1 billion based on U.S. and European sales. Xigduo peak sales estimates are currently unclear, but it could follow in Forxiga's footsteps if it gains approval in the U.S. as well.

This is a positive development for AstraZeneca, which has been trying to diversify its portfolio away from its four main blockbusters -- the antipsychotic Crestor, the statin Crestor, the acid reflux treatment Nexium, and the asthma treatment Symbicort -- which generated combined revenues of $16.2 billion in fiscal 2012.

Nektar offers up 8.5 million shares in a new public offering
Last but not least, Nektar Therapeutics could slump today after it commenced an underwritten public offering of 8.5 million shares of common stock. Although the sale will inevitably dilute the value of the company's 116 million outstanding shares, Nektar is still up more than 50% over the past 12 months on optimism regarding its products and pipeline.

Nektar has brought nine treatments to market with industry heavyweights such as Roche (NASDAQOTH: RHHBY), Pfizer (NYSE: PFE), and Amgen (NASDAQ: AMGN) for a variety of indications in immunology, oncology, nephrology, and surgical imaging. These products all use Nektar's polymer conjugate technology, which can enhance a drug's effectiveness.

Nektar currently has five treatments in phase 3 trials, for a wide variety of indications including opioid-induced constipation, late-stage breast cancer, pneumonia, bronchiectasis, and hemophilia A. It is partnered with AstraZeneca, Bayer (NASDAQOTH: BAYRY), and Baxter (NYSE: BAX) for these treatments. The company also holds royalty-bearing licensing partnerships with Ophthotech (NASDAQ: OPHT), Regado Biosciences (NASDAQ: RGDO), and Allergan (NYSE: AGN).

Nektar's product sales, partnerships, and licensing agreements have helped it generate $118 million in revenue over the first three quarters of fiscal 2013 -- a big jump from the $81 million in revenue it reported for the entirety of fiscal 2012.