Joby Aviation Inc. stock JOBY,+40.22% jumped 8% Thursday premarket to extend its weekly gains to 42%. The maker of electric air cabs announced that it received a $100-million investment from SK Telecom Co. Ltd. SKM, -1.12% .. This news comes a week after the stock experienced a more than 40% rise after the company gained a step closer to commercial flights. Proponents say that eVOTL aircraft are quieter and safer to operate than internal-combustion-engine helicopters. Joby intends to begin commercial operations by 2025. As part of a new partnership, South Korea’s largest telecoms firm is investing in Joby. Joby stated that the agreement executed on 27th June “allows Joby to join SKT for Korea’s K-UAM Grand Challenge” It explained that the Challenge is a demonstration program, run by the Korean Ministry of Land, Infrastructure and Transport, designed to encourage the adoption of aerial ridesharing. The stock is up 167% year-to-date, while S&P 500 SPX, 0.04% is up 14%.