Sirius XM Holding Inc is trading 4.2% up at $28.59 in pre-market trading after it was announced the company will be added to the S&P MidCap 400 index.
- S&P Dow Jones Indices announced that SIRI will replace Masimo Corp. (MASI) in the index, effective before the market opens on Thursday, June 11.
- Inclusion in a major index like the S&P MidCap 400 typically leads to increased demand for a stock from index-tracking funds and ETFs, which must buy the shares to rebalance their portfolios.
- The stock reacted positively to the news, rising as much as 5% in after-hours trading on Monday following the announcement.