The index provider said Sirius XM will take Masimo’s (MASI) slot in the benchmark effective prior to the market open on Thursday, June 11.
- The change stems from Danaher Corp.’s pending acquisition of Masimo.
- Danaher agreed in February to buy Masimo for $180 per share in cash, a deal valued at roughly $9.9 billion including debt.
- The addition to the index marks a milestone for Sirius following its corporate reorganization last year.
Shares of Sirius XM Holdings (SIRI) rose 5% in after-hours trading on Monday after S&P Dow Jones Indices announced the company will replace Masimo Corp. in the S&P MidCap 400, a move expected to trigger buying by index-tracking funds and ETFs.
The index provider said Sirius XM will take Masimo’s (MASI) slot in the benchmark effective prior to the market open on Thursday, June 11. The change stems from Danaher Corp.’s (DHR) pending acquisition of Masimo, which is slated to close prior to the open on June 10, with Masimo’s shares to be suspended from trading effective June 11.
Danaher Masimo Deal
Danaher agreed in February to buy Masimo for $180 per share in cash, a deal valued at roughly $9.9 billion including debt.
Masimo shareholders approved the transaction in May, and the companies have said the deal is on track to close in the second half of 2026, subject to remaining regulatory clearances. Once complete, Masimo will operate as a standalone business within Danaher’s Diagnostics segment.
Sirius XM, with a market capitalization of approximately $9 billion, fits squarely in the mid-cap range. The addition to the index marks a milestone for Sirius following its corporate reorganization last year and comes as the company continues to emphasize its audio entertainment platform, including satellite radio, streaming, and advertising partnerships.
How Did SIRI Retail Traders React?
On Stocktwits, retail sentiment around SIRI stock stayed within the ‘bearish’ territory over the past 24 hours, while message volume remained at ‘low’ levels.
SIRI stock has gained 34% this year owing to multiple catalysts, including Berkshire Hathaway's large and growing stake in the company and a major YouTube audio advertising partnership.
For updates and corrections, email newsroom[at]stocktwits[dot]com.<
