There’s more bad news for Twitter today as a group called OurMine hacked accounts for Netflix, Marvel Entertainment, and NFL Network.

OurMine sent tweets on the victims’ feeds, mostly saying that it was testing their security. For example, it told Netflix US followers: “Hey, it’s OurMine. Don’t worry we are just testing your security, contact us to tell you more about that” followed by a Gmail address.

It ran nearly identical messages on Marvel Entertainment’s feed. Most have been deleted.

TechCrunch, which has investigated OurMine, says it’s “a small group of young people (one of whom might be a Saudi teen).” But it “typically doesn’t do much” with the accounts it hacks except to encourage people to reach out to find out ways to improve online security.

Others who the group has hit in the past include actor Channing Tatum, Google CEO Sundar Pichai, TechCrunch, and former Twitter CEO Dick Costolo.

Twitter shares are down 4.5% today following yesterday’s reports that it’s losing two top execs: Chief Technology Officer Adam Messinger and VP Product Josh McFarland. The company has lost at least a dozen execs at the VP level or higher in 2016, Recode reports.