What happened

GW Pharmaceuticals (GWPH) stock jumped 20.5% last month, according to data from S&P Global Market Intelligence. It tacked on another 3.1% on Friday, the first day of March.

The British biopharmaceutical company develops prescription drugs derived from cannabinoids, chemical substances found in marijuana.

For context, the S&P 500 index returned 3.2% in February.

Overhead view of various types of pills lying on a surface with a marijuana leaf over them and three pill bottles lying on their sides adjacent to the pills.

Image source: Getty Images.

So what

We can attribute GW Pharmaceuticals stock's strong performance last month to the company's release on Feb. 26 of fourth-quarter results that were better than anticipated. Revenue soared 68% year over year to $6.7 million, well above the $5.35 million Wall Street was expecting. Net loss of $0.20 per share was flat with the year-ago period, though it handily beat the consensus estimate of $2.90.

"The big story for GW Pharmaceuticals in the fourth quarter was a great U.S. launch for cannabis-based drug Epidiolex," as my colleague Keith Speights wrote following the release. For the two months in Q4 that the drug was available in the U.S., sales tallied $4.7 million. Analysts were widely anticipating sales of about $3 million, according to Keith. Momentum into 2019 is strong, with filled prescriptions in January increasing about 150% over December, GW said in the earnings release. 

Check out the latest earnings call transcript for GW Pharmaceuticals.

Epidiolex launched in this country on Nov. 1 after receiving approval from the U.S. Food and Drug Administration in June to treat patients with two rare forms of epilepsy. It's the first drug derived from the cannabis plant that's received the green light from the FDA.

Shares of GW Pharmaceuticals jumped 13.8% on Feb. 27 following the company's release of Q4 results the day before.

GWPH Chart

Data by YCharts. 

For 2019, GW Pharmaceuticals stock is now up a whopping 82%. 

GWPH Chart

Data by YCharts.

Now what

As I've previously written, "GW stock's direction for the next couple years will likely highly depend upon how well Epidiolex is selling, so this is the key thing investors should focus on in fiscal 2019. Pipeline progress is also important."