The apps you download onto your smartphone are sharing more data about you than you probably realize.
More than 90 percent of the top 200 apps—100 paid and 100 free—in Apple's App store exhibit "risky behavior," according to a report released Tuesday by Appthority, an app risk management company. The top 200 Android apps were not quite as bad, with about 83 percent showing "risky behavior," according to the report.
(Read more: Snapchat rival hopes to pounce on security breach)
What qualifies as "risky behavior?" Examples include location tracking, accessing your contacts and/or your calendar and sharing your data with third-parties like ad networks.
"Overall, iOS shares more data than Android, and free apps share more information than paid apps," said Domingo Guerra, president and founder of Appthority. "But paid apps share more information than people might think."
"Permissions on apps aren't very clear and even if they do say what they are going to collect, they don't always spell out what they are going to do with that data," Guerra said.
Overall, apps on Apple's platform—both free and paid—share more data than Android apps because Apple customers' information is more valuable, Guerra said. Apple customers tend to spend more money, thus ad networks prefer to target them, he said. (Ad networks are a big part of how free apps make money.)
"Apple's own popularity and premium audience attracts ad networks to target iOS users more than Android users," said Guerra. "More success for the developer comes at our expense."
In the free app category, though, more Android apps share data with ad networks (58 percent of the top 100), than Apple (48 percent).
It's a common misconception that paid apps don't share customer information with third-parties, but that's not the case, Guerra said.
According to the report, 27 percent of the top 100 paid apps for iOS share data with advertising networks or analytics companies. It's about 24 percent for Android.
"One of our assumptions was if you don't pay for an app you are the product. But 27 percent of paid apps working with ad networks is still pretty high. While free apps collect more data, by no means are consumers completely safe just because they paid for an app," Guerra said.
—By CNBC's Cadie Thompson. Follow her on Twitter @CadieThompson.