Some biotech string to start your week:

What the (bleep) just happened?

Before I look ahead, the biotech train wreck in the rearview mirror must be addressed.

The Nasdaq Biotechnology Index lost 21% of its value in January, the third-worst monthly performance in the measure's history. The S&P 500 fell 5% in January. For perspective, the worst month ever for the NBI was March 2000, when the index fell 25%. (Hat tip to @sport234a2b for the historical NBI performance metrics.)

Just eight biotech and drug companies closed January at a higher stock price than where they ended 2015, according to (I screened for biotech and drug stocks with market caps $300 million or greater to weed out micro and penny stocks.)

The January carnage is everywhere. Big-caps: Celgene(CELG) - Get Report -16%, Gilead Sciences(GILD) - Get Report -18%. Mid-caps: Seattle Genetics(SGEN) - Get Report -27%, Vertex Pharma(VRTX) - Get Report -28%, Medivation (MDVN) -32%. Small-caps: Epizyme(EPZM) - Get Report -43%, Cempra (CEMP) -45%, Sage Therapeutics(SAGE) - Get Report -42%.

The fall from 52-week highs is even scarier. I won't even go there.

Why the (bleep) are biotech stocks tanking and when the (bleep) does the selling end?

Why? Because positive sentiment and momentum -- the high-octane fuels which makes biotech stocks move higher -- are in very short supply. Because generalist investors have pulled their money from the biotech sector to invest elsewhere. Because politicians from both sides of the aisle are calling drug companies greedy for the way they price drugs. Because the biotech sector isn't exactly helping itself right now. Fourth-quarter earnings and 2016 guidance have been lackluster. Buzz-worthy, stand-up-and-cheer clinical trial victories haven't materialized.

When? I have no idea. The people telling you biotech and drug stocks are cheap so buy now (!!) don't know. No one knows. From a fundamental science perspective, the biotech sector isn't falling apart. That's comforting to an extent, except investors don't care. At some point they will care again. I realize this is all very comforting to hear.

A new Sarepta FDA panel date -- maybe.

I heard a rumor the Food and Drug Administration has settled on a new date for the delayed Sarepta Therapeutics(SRPT) - Get Report eteplirsen advisory panel. I'm hesitant to post the exact date here because I've been unable to confirm, but the rumored date is in late February. 

If FDA has managed to align the calendars of participants in Sarepta panel, we should hear something definitive this week.

Gilead: A few thoughts.

Gilead reports fourth-quarter and 2015 earnings on Tuesday after the markets close. This will be the first opportunity for Gilead management to comment publicly on competition in the hepatitis C drug market following Merck's(MRK) - Get Report decision last week to price its newly approved therapy, Zepatier, at $54,600 -- a significant list-price difference from the $80,000 cost of Harvoni.

Gilead lost another 5% to $82.70 Friday on Merck's hepatitis C drug pricing disclosure. Gilead shares last closed this low on June 27, 2014. The company's forward (2016) price-to-earnings ratio has dropped to 6.8.

How low is that? I cribbed the Gilead 10-year P/E chart below from The Wall Street Journal health care and industrials reporter Charley Grant, who posted it onTwitter(TWTR) - Get Report Friday. (Read all of Charley's stories and follow him on Twitter -- he's really good.)

Gilead is trading at an historically low P/E multiple because investors are worried a lot about what happens to the "E" when hepatitis C drug revenues start to tail off in a few years. (Gilead argues hepatitis C drug sales will have a much longer tail, but investors are, generally speaking, skeptical.)

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Note the timing of the last Gilead P/E low point, which came in November to December 2011. Raise your hand if you remember what happened in November 2011, right before Gilead's P/E ratio started to recover. Pat yourself on the back if you said the $11 billion acquisition of Pharmasset and its golden hepatitis C drug assets.

Interesting, eh?

On Friday, Gilead said President and Chief Operating Officer John Milligan is being promoted to CEO. He replaces current CEO John Martin, who is becoming executive chairman.

The announcement basically formalizes the leadership structure in place at Gilead for many years. Investors have long recognized Milligan as Gilead's de facto CEO overseeing the company's operations, while Martin acted more like a chairman responsible for Gilead's strategic vision.

Baird analyst Brian Skorney believes (maybe "hopes" is a better word) the timing of the Milligan-Martin step-up promotion hints at something big coming from Gilead. Martin was CEO for Gilead's two transformational deals -- the acquisitions of Triangle Pharmaceuticals in 2002 and Pharmasset in 2011.

Perhaps Gilead's board is elevating Milligan to the CEO seat now so he can take credit for Gilead's Transformation Deal No. 3 -- whatever that might be, Skorney speculates. At the very least, he adds, it would be odd for Gilead to promote Milligan now just to allow the company to crumble under him.

Biotech IPOs. No, I'm not kidding.

BeiGene, a China-based cancer immunotherapy developer, and Editas Medicine, the CRISPR gene editing startup, are on the IPO pricing docket for this week, according to Renaissance Capital.

BeiGene's current plan is to sell 5.5 million American Depositary Shares (each worth 13 common shares) priced in the range of $22 to $24. Editas is offering 5.9 million shares for $16 to $18. Everyone will be watching these IPOs closely to see if they get out on time and within the expected price range, and how well they perform in the days that follow.

Good luck!

Health care earnings season continues.

Tuesday: Gilead, Pfizer (PFE) - Get Report and Mallinckrodt(MNK) - Get Report .

Wednesday: Alexion Pharma(ALXN) - Get Report , GlaxoSmithKline(GSK) - Get Report and Merck(MRK) - Get Report .

Thursday: AstraZeneca(AZN) - Get Report .

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.