According to
http://art-of-tactic.com/ru/istorich...zvod_1941_goda a platoon (vzvod) in 1941 had 5 tanks in case of light and medium tanks and 3 tanks in case of heavy or flamethrower or amphib tanks.
A company should have 2 or 3 platoons.
Other source (Magnuski) writes about 15 T-26 in company from 1936 and 17 T-26 from 1938.
There are schemes from 2/41 of:
- a heavy tank co, with 3 x 3 +1 tanks (10)
http://shot.qip.ru/003M7J-2008a0M/
- a medium tank co, with 3 x 5 +1 tanks (16)
http://shot.qip.ru/003M7J-2008a0N/
My educated guess is, that the units should be same size - until heavy losses at least.