Nio (NYSE:NIO) stock is slumping 5% today despite a new deal with fellow Chinese car maker GAC to establish battery swap-enabled passenger cars and battery swap stations cross-compatible between both vehicle makes.Nio and GAC signed the strategic cooperation agreement earlier today, on May 8, in Guangzhou. GAC is headquartered in Guangzhou, China.“The cooperation will amplify the two companies’ respective strengths in technology and operations, and push forward the unification of battery standards and opera ...