a portion, esp a block of shares usu supplementary to an already existing issue
any of a series of sets, portions, etc of something made available at a particular time
The discs are to be issued in alphabetical order of composer: the first tranche includes some Bartok, the nine Beethoven symphonies, the Brahms symphonies and works by Bernstein himself — Daily Telegraph
[French tranche slice, from Old French trenchier, trancher to cut, from Latin truncare to lop off, maim]