Keep in mind... the fact that most of those tech companies are based in California has some relevance - California is (always has been) a progressive-leaning state.
Combine that with the factor blip mentioned regarding the average age of people employed in said tech companies being rather young, and that young people are overwhelmingly throwing their support behind Bernie in this election cycle; Well, there you've got two factors lending quite a bit of weight as to why Bernie seems to be the favorite of many tech companies.
However, going by industry, tech companies do not make up the greater proportion of donations, see this page placing (interestingly enough) retired individuals as making up the largest amount of combined donations while Electronics Mfg. & Equip comes in at a modest 7th place in the list of most substantial donations by industry.
- 1 Retired $1,086,825
- 2 Education $580,328
- 3 Lawyers/Law Firms $300,057
- 4 Health Professionals $296,931
- 5 Misc Business $286,682
- 6 Democratic/Liberal $275,490
- 7 Electronics Mfg & Equip $268,74