Two large mutual life insurers today announced executive appointments that could affect who eventually will end up running the companies.

The board of New York Life Insurance Company, New York, has picked Theodore Mathas, 40, to be president of the company.

The board of Massachusetts Mutual Life Insurance Company, Springfield, has named Roger Crandall, 42, and William Glavin Jr., 48, to be that company’s co-chief operating officers.

Mathas, who has been chief operating officer of New York Life since 2006, will succeed Frederick Sievert, 59, who is retiring from New York Life after 15 years of working for the company.

Mathas will continue to be New York Life’s COO, and Sy Sternberg will continue to be the company’s chairman and chief executive officer, the company says.

Mathas began working for New York Life in 1995, as an officer in the asset management department. He has a bachelor’s degree from Stanford University and a law degree from the University of Virginia.

Over at MassMutual, Crandall has been an executive vice president and chief investment officer of MassMutual. Crandall will keep his current responsibilities and gain responsibility for the company’s retirement services division, MassMutual says.

Crandall began working for MassMutual in 1988. He has a bachelor’s degree from the University of Vermont and a master’s degree in business from the University of Pennsylvania.

Glavin, a former president of the Scudder Funds, has been working for MassMutual since 2003. He has a bachelor’s degree from the College of the Holy Cross.

Stuart Reese will continue to be the chairman, president and CEO at MassMutual, MassMutual says.