The board cautioned investors to use the company's valuation metrics "with a higher degree of caution and less certainty" than normal.
The 20-stock index gained 2.2% to 1,522.78. It's now up 30.4% year to date.
The transaction, expected to close in the third quarter of 2023, will create a single class of stock for the satellite radio giant.
The group's re-signing lifted K-pop stocks while Spotify's share price enjoyed a double-digit increase, bringing the index's year-to-date gain to 26.9%.
Stock in the K-pop agency soared on the news.
The company's announcement that it would cut 17% of its global workforce added $2.6 billion to the streaming giant's market capitalization.
The Billboard Global Music Index dropped 0.2% to 1,449.08, bringing its year-to-date gain to 24.1%.
The Billboard Global Music Index gained 2.6% this week, bringing the year-to-date gain to 22.1%.
The Billboard Global Music Index declined 0.3% to 1,390.68, lowering its year-to-date gain to 19.1%.
The Billboard Global Music Index improved 6.9% this week as 18 of the 20 stocks posted gains.
