Novo shares rose 2.1% in Copenhagen, boosting its market capitalization to the equivalent of almost $425 billion. LVMH fell 0.8% in Paris, valuing the company at about $420 billion. It was only this year that the French luxury conglomerate passed the milestone of becoming Europe’s first company with a market value exceeding $500 billion, only for the stock to slip back since.

The success of Novo’s Wegovy and Ozempic injectable drugs has sparked something of a gold rush in the pharmaceutical industry and some analysts predict such treatments could become among the best-selling medicines ever. About 40 companies are chasing after Novo for a share of the market, led by Eli Lilly & Co., which expects to get US approval this year to use its Mounjaro diabetes drug to treat obesity.

Behind the rapid emergence of the Novo drugs is the GLP-1 agonist, a molecule initially identified to help people with diabetes regulate their blood sugar, but whose appetite-suppressing effects were quickly found to also help people lose weight. The drugs have since become so popular that regulators around the world have raised alarm that Ozempic may not reach diabetics who depend on the injection.

Because of this, GLP-1 drugs may become the victims to their own success. On Aug. 23, regulators in Novo’s native Denmark proposed limits on subsidies for GLP-1 treatments.

Novo’s stock has more than quadrupled since the end of 2018, overtaking other European behemoths like Nestle SA, as well as pharmaceutical rivals Roche Holding AG and Novartis AG. The latest boost came in August when a landmark trial showed that Wegovy cuts the risk of heart disease by a fifth. The study may broaden access further by aiding Novo in reimbursement discussions with insurers who might otherwise balk at Wegovy’s cost.

Also in August, the Danish company raised its profit and sales outlook for the year, citing growth fueled by demand for Wegovy and Ozempic.

With the global market for obesity treatments expected to explode in the coming decade, Novo and Eli Lilly were in July tipped by Citigroup Inc. analysts to dominate what they described as a “structural duopoly.”

Still, it’s not all smooth sailing. Novo has also said the supply of Wegovy will continue to be restricted in the US as the drugmaker struggles to expand production. Reuters reported Aug. 23 that Novo hired US-based Thermo Fisher Scientific Inc. as its second contract manufacturer of the drug.

On Friday, Novo Chief Executive Officer Lars Fruergaard Jorgensen told Bloomberg TV that his company is “basically selling everything we can produce and when it comes to manufacturing, we’re ramping up significantly as we speak.”