All three major US stock indexes were up in late-morning trading Monday after performing strongly last week.

In company news, Pfizer (PFE) said Monday it has entered into a definitive agreement to acquire Metsera (MTSR) for $47.50 per share in cash, valuing the company at about $4.9 billion. The deal will add differentiated oral and injectable incretin, non-incretin and combination therapy candidates to its pipeline. Pfizer shares were up 2.2% around midday, while those of Metsera shares were up 62.4%.

Oracle (ORC) would provide security for an new US version of TikTok's algorithm as part of a deal to sell the Chinese-owned app to a group of American investors, Bloomberg reported Monday, citing a White House official. Separately, Oracle said Monday it promoted Clay Magouyrk and Mike Sicilia to the roles of chief executive officers. Magouyrk previously served as president of Oracle Cloud Infrastructure, while Sicilia previously served as president of Oracle Industries. The company also said it appointed former CEO Safra Catz as executive vice chair of the board of directors. Oracle shares were up 4.2%.

T-Mobile US (TMUS) said Monday it has named Chief Operating Officer Srini Gopalan as CEO, effective Nov. 1. Gopalan will replace Mike Sievert, who is taking over the newly created role of vice chairman at T-Mobile. Shares of T-Mobile were up 0.1%.

Cosan (CSAN) shares fell sharply on Monday after the Brazilian commodity conglomerate announced plans to issue up to 2 billion shares through two public offerings. Cosan shares were down 23.7%.

Price: 24.56, Change: +0.52, Percent Change: +2.18