The fourth stage of the 58th Giro Ciclistico Internazionale della Valle d'Aosta Mont Blanc, from Pont Saint Martin to Coumarial (Fontainemore), set the race hierarchies of the race.

The start was really fast. A small group of escapees won the first Sprint Catch of Montjovet (Sean Flynn of Tudor Cycling) and the second of Saint Vincent (won by Robin Skivild of Uno X Dare). Skivil, the Danish rider, led the race in the next phases, taking the lead on the ramps of the Col d'Arlaz where he won the KOM, then the KOM of Col d'Arlaz, then KOM Col Tsecore and the KOM Col de Joux.

The yellow jersey's teammates were in control of the race leading the peloton. Skivild's feat ended at Pont Saint Martin, however, where the peloton caught up with him at the foot of the Perloz climb. Here, Groupama immediately took the lead, with Reuben Thompson and yellow jersey Martinez in the sprint, joined by Welay Berhe Hagos (EF) and Oscar Onley (DSM). Thompson, Martinez and Berhe Hagos went through the terrifyingly short climb of KOM Perloz and again in the same order on KOM Fabiole, getting rid of fellow rider Onley. But the Groupama FDJ duo continued to force the pace all the way to Fontainemore and were leading alone on the final climb to Coumarial. The two overall leaders continued at a steady pace and their gap grew on Marco Frigo (Israel) and on Simone Raccani (Italian national team).

At the finish in Coumarial, Thompson and Martinez finally came in hand-in-hand, with Raccani third at 43", Onley fourth at 1' 40" and Frigo fifth at 2' 05". In the GC, Lenny Martinez (Groupama FDJ) reconfirmed his position in the yellow Eaux Valdotaines and white Vallée d'Aoste jersey. Reuben Thompson (Groupama FDJ) is second, while Simone Raccani is third and opens the way to Marco Frigo (4th) and Riccardo Ciuccarelli (5th). The red and white Haute Savoie Sprint Catch jersey goes to Sean Flynn (Tudor Pro Cycling) while the CVA Energie KOM jersey is taken by Reuben Thompson.