Shares of Sirius XM Holdings Inc. /zigman2/quotes/201205073/composite SIRI -1.48% shed 2.0% in morning trading Friday, after J.P. Morgan analyst Sebastiano Petti backed away from his long-time bullish stance on the satellite radio company, citing expectations of slowing auto sales, because of semiconductor shortages, and rising expenditures related to satellite builds. Petti cut his rating to neutral, after being at overweight at least as long as since January 2019, while cutting his stock price target to $7 from $8. Following management comments at recent industry conferences, Petti said he raised his third-quarter self-pay net subscriber additions estimate to 400,000 from 315,000 on record second-quarter trial starts, low churn, rising penetration and higher digital-only subscriptions. However, he trimmed his 2021 self-pay net adds estimate to 1.10 million from 1.15 million and dropped his 2020 estimate to 750,000 from 1.05 million, saying the chip shortage is likely to become "more acute in coming quarters." The stock has lost 3.2% year to date, while the S&P 500 /zigman2/quotes/210599714/realtime SPX -1.18% has gained 17.2%.