The five biggest tech companies have applied for more than 52,000 patents since 2009, according to a report by CB Insights. And the applications tell a story about where each of the tech giants is strong and where they’re weak.

For instance, the patent applications show that Apple lags badly in artificial intelligence, one of the fastest-growing segments in tech. Microsoft leads AI with more than 200 patent applications since 2009, and Google comes in second with 150. Apple came in last among the top five.

Google, meanwhile, is No. 1 in vehicle patents, a sign of its interest in self-driving cars. Apple is No. 2 in that category, and Amazon is No. 3.

Microsoft has a sizable lead over the other big tech companies in augmented reality and virtual reality patent applications, given its interest in its HoloLens AR headset.

CB Insights tracks the patent activity of the biggest tech companies.

Above: CB Insights tracks the patent activity of the biggest tech companies.

Image Credit: CB Insights

Microsoft has filed for the most patents among the five tech giants. Between 2009 and 2016 year-to-date, Microsoft applied for over 16,500 patents, about 2,000 more than Google, which was in second place. Apple was in third and Amazon a distant fourth.

Facebook lags way behind the other four in patent filing activity. Among its filings were patents related to the automation of flagging and removal of objectionable content, dating back to 2015.

Google’s recent patents show it is moving into autonomous vehicle tech and wearables, according to the report.

One notable Apple patent is in autonomous vehicle tech, pertaining to “collision avoidance of arbitrary polygonal obstacles.” This shows the Cupertino, Calif.-based company is still very active in autonomous driving software even if, as reported, it will not manufacture an actual car, the report said.

Amazon’s recent patents show it moving away from consumer devices like ebook readers and tablets and toward drones and cybersecurity. Amazon also received a patent this month for devices that can identify people according to their blood flow and heart rate. It uses a camera device that may monitor blood flow to an individual’s face. This tech is interesting in light of Amazon’s Go store concept that will need to identify individuals in-store in order to eliminate checkout lanes and cash registers, CB Insights said.