Areas of investment by Big Tech

Mobile Hardware : Apple, Google
Mobile OS and App store : Apple, Google
Voice : Apple, Google, Amazon
Home(Camera, speaker, other devices) : Apple, Google, Amazon
Social : Facebook
Communications : Apple, Facebook, Google
Video : Google, Amazon, Facebook
Search : Google, Microsoft
Ads : Google, Facebook, Amazon
Cloud : Apple, Google, Microsoft
Computer Hardware : Microsoft, Apple
Computer OS : Apple, Microsoft
Productivity Suite : Microsoft, Google
e-Commerce : Amazon, Facebook