Allergan (UNKNOWN:AGN.DL) and MannKind (NASDAQ:56400P706) both released pivotal news Friday that could have a major impact on their respective share prices in the coming week.

Allergan's hopes of remaining independent are fading
On Friday, Allergan said it had agreed with Bill Ackman's Pershing Square Capital Management that a special meeting of shareholders would not trigger a "poison pill" measure that would have allowed shareholders to buy company stock at a discount in order to drive the price of a takeover up markedly. This agreement settles a lawsuit launched by Pershing Square earlier this month. 

Pershing Square, and now Paulson, have purchased large interests in Allergan in hopes of forcing the company to accept a merger with Valeant Pharmaceuticals (NYSE:BHC)

Although Valeant has reportedly offered up to $53 billion for the Irvine, Calif.-based Botox maker, Allergan's management has stated that such an offer grossly undervalues the company.

Valeant's initial offer would have come at roughly a 50% premium to Allergan's share price before this news hit the Street, making it one of the richer tender offers seen so far this year. After failing to convince management that this deal was in its best interest, Pershing Square plans to take the issue directly to Allergan's shareholders. 

Allergan's chances of remaining independent appear to be fading. I think it's unlikely shareholders will vote down a merger given that Allergan's current share price has clearly cooked in this offer, as illustrated by the chart below.

AGN Chart

AGN data by YCharts.

A vote against the merger would likely result in a major downturn in Allergan's share price, akin to what happened to AstraZeneca after the British company last month rebuffed Pfizer's buyout attempt. 

MannKind's inhaled insulin product officially approved
MannKind's long regulatory path for its inhaled insulin product Afrezza and delivery apparatus Dreamboat has finally come to an end, with the FDA approving the product on Friday. That's the good news.

The bad news is that the product will carry a warning on the box regarding the risk of acute bronchospasm in patients with asthma and chronic obstructive pulmonary disease. MannKind -- or any potential marketing partner -- is also required to carry out four post-marketing studies: one to examine Afrezza's safety and efficacy in children, another on the potential risk for lung cancer and heart problems, and two of the drug's pharmacokinetics and dosing.

After the news of the approval hit the Street, MannKind shares first plunged and subsequently shot upward by 10% in after-hours trading. My take on this erratic trading is that some investors decided to sell the news, while the furious after-hours activity reflects the strong belief of some MannKind longs that the best is yet to come.

Keep in mind that MannKind hasn't inked a partnership yet, but its market cap is rapidly closing in on the $4 billion mark. Moreover, MannKind shares have skyrocketed by 92% this quarter, suggesting that at least some of this approval has been baked into the share price.

MNKD Chart

MNKD data by YCharts.

Although I don't want to sound like a broken record, I think the details of any partnership are going to be crucial to MannKind's valuation moving forward. As such, you may want to take a cautious approach with this volatile biopharma for the time being.