If you look at who's contributing to various presidential candidates, you'll find that many donors work for law firms, banks, unions or universities. But for Bernie Sanders, you'll notice something else: donations from a whole bunch of people who are employed by tech companies.

This wouldn't be worth mentioning except for the fact that Sanders appears to have a broad-based appeal among Silicon Valley workers compared with his rivals. According to the Center for Responsive Politics, Sanders's campaign committee seems to be by far the biggest recipient of donations from employees of Alphabet (Google's parent company), Apple, Microsoft, Amazon.com and Intel.

By contrast, the same list for Hillary Clinton shows hardly any tech-company workers. Instead, it's largely packed with names like Corning, Time Warner and Dish Network.

It's important to point out that the donors here aren't the companies themselves — just very politically engaged people who happen to work there. The rules don't require individual donors to disclose the names of their companies, either, so what we're seeing in these lists is just what the most transparent among us have chosen to make available. There may be other tech-company donors who've decided to hide who they work for.

This sets up a few possibilities. It's conceivable, for instance, that Clinton's support among tech companies is actually higher than what we can observe from her list, which looks like this.

As you can see, the only tech company represented is Alphabet.

Another possibility is that tech-industry folks are donating to Clinton but in amounts too small to break into the lists we're looking at. Without knowing more about the donors themselves, it's hard to say which candidate Silicon Valley truly favors. What we can say is that Sanders appears to have much more support than Clinton across a wider range of tech companies, even if the amount of that financial support is relatively small.

But despite Sanders's apparent support from within some tech companies, polls have shown that Clinton is likely to dominate in California's Democratic primary. Sanders is polling below 20 percent in the state.

For comparison's sake, the tech industry is almost completely absent from the donor lists belonging to the major GOP presidential candidates, which can be found here, here and here. It's worth noting that California has not been a very high performer for conservative politicians at the presidential level.