As reported by Kicker, Tiago Tomás will remain on loan with Stuttgart from Sporting CP.
The 19-year-old forward played 14 times this season, scoring four goals in the process.
Tomás will remain in Germany until the end of next season when they have an option to buy the striker for €15m.
Stuttgart will reportedly exercise their €3.2m purchase option on central-defender Konstantinos Mavropanos whilst Hiroki Ito will also join on a permanent basis for €400,000 from Jubilo Iwata.
Mavropanos played a crucial role this season playing 33 times in all competitions and scoring on five occasions.