Apple's stock was downgraded for a second time since its earnings report, this time by Rosenblatt Securities, which said it has lowered its expectations for iPhone production and shipments.

The firm cut its rating on the largest public company in the U.S. to neutral from buy, telling clients that it will be difficult for Apple to offset weaker volume with higher selling prices in the second half of 2019.

"Calendar fourth-quarter guidance reflects our cautious view on weaker than expected sell-through and production reductions for iPhone XS/XR," analyst Jun Zhang wrote in Friday's note. We "downgrade to neutral."

Apple also was downgraded by Bank of America Merrill Lynch on Friday.