What happened
Shares of Vir Biotechnology (VIR 1.49%) were vaulting 12.8% higher as of 3:07 p.m. EST on Tuesday. The big jump came after the company announced news about separate collaborations with Gilead Sciences (GILD 2.20%) and GlaxoSmithKline (GSK 0.92%).
So what
Partnerships with big drugmakers often serve as positive catalysts for small biotech stocks. It's not surprising that Vir's updates about two different collaborations especially excited investors.

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Vir and Gilead plan to work together on a phase 2 study evaluating Vir's VIR-2218 with Gilead's selgantolimod in treating individuals infected with the hepatitis B virus (HBV). In addition to this combo, study participants could also receive Gilead's HBV drug Vemlidy.
Vir and GlaxoSmithKline partnered last year to develop COVID-19 therapies. The two companies announced today that they intend to kick off a phase 2 study evaluating antibody therapy VIR-7832 in treating COVID-19 patients this quarter.
This new study with GSK was likely the bigger factor driving Vir's stock higher today. GSK invested $250 million in Vir in April 2020. No financial details of Vir's collaboration with Gilead were released. Each company will retain full rights to their products involved in the phase 2 study. Vir and Gilead stated that they "will discuss the potential path forward for any future combination studies based on the outcome of the phase 2 trial."
Now what
The next key catalyst for Vir could be on the way soon. Interim results from a late-stage study of VIR-7831, another antibody therapy included in Vir's collaboration with GSK, should be announced early this year.