#$once

Biotech stocks are over-valued! Drug prices are not sustainable! Investors won't digest more IPOs! The biotech bubble is about to POP! Nationwide Insurance killed a cute kid during the Super Bowl!!!

You've heard these concerns and more but one month into 2015, investors continue to climb the wall of worry, pushing the major biotech stock indices higher and higher.

Here's where we stand with January trading under our belts.

Biotech stocks are outperforming the broader market by a healthy margin, just like they did in 2014. [If you're wondering, the XBI and NBI were up 15% and 8% in January 2014, respectively.]

Here's a snapshot of what's buzzing in biotech:

1. Gene therapy is super-hot. Spark Therapeutics priced its IPO on Friday at $23 per share, opened at $45 and closed at $50. Spark is developing one-time treatments for genetic diseases. The company's lead program is in a late-stage study for a rare form of blindness. 

Bluebird Bio remains the most talked about and best-performing gene therapy stock (even if the $2.7 billion valuation is cited as evidence of an over-heated biotech sector) but there isn't a laggard in the bunch over the past three months, with the possible exception of Avalanche Biotechnologies. 

Pay close attention to the gene therapy stocks, including newly IPO's Spark, for the rest of 2015. 

2. Hepatitis C drug marketing battle rages on. Abbvie shares were weak Friday on lower-than-expected sales guidance for Viekira Pak. The company said it expects sales of the hepatitis C therapy to achieve an "exit rate" of $3 billion by the end of 2015. Enanta Pharmaceuticals shares fell Friday in sympathy. Enanta receives a royalty from Abbvie based on Viekira Pak sales. 

Gilead Sciences reports fourth quarter and 2014 earnings on Tuesday after the close. 

Here's how the three big Hep C stocks have performed since Abbvie secured Viekira Pak approval on Dec. 19:

3. Big-cap biotech performance: Biogen Idec staged a fourth-quarter earnings relief rally Friday to gain the top spot. Investors had been worried that Biogen's multiple sclerosis pill Tecfidera might under-perform in the fourth quarter, but the company pulled out better-than-expected sales. Celgene, Alexion Pharma and Amgen all reported fourth-quarter earnings and 2015 guidance basically in-line with expectations.