Novo Nordisk ( NVO ) is falling by over 20% in Friday's pre-market trading after its experimental weight-loss shot CagriSema was found to help recipients lose less weight than previously forecasted in its clinical trial.

Yahoo Finance senior health reporter Anjalee Khemlani expands upon this story and compares Novo Nordisk's stock performance with that of GLP-1 drug competitor Eli Lilly ( LLY ).

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This post was written by Luke Carberry Mogan .