Is Leica's Brand New Lens Actually Made by Sigma?

When Leica announced its brand new Vario-Elmarit-SL 24-70mm f/2.8 ASPH last week, it was interesting to note how similar it is to the 24-70mm f/2.8 DG DN Art released by Sigma last year. Has Sigma built this lens in Japan so that Leica can stick a red dot on it? The similarities are striking. Both have 19 elements in 15 groups with 11 rounded aperture blades — nothing surprising there. Looking a little closer, the minimum focusing distance is all but identical: 7.1” (18cm) on the Sigma, and 7.09 “ (also 18cm, apparently) on the Leica.