Hancock beefs up mutual funds. (John Hancock Mutual Funds Inc.'s marketing strategies)

John Hancock Mutual Funds rang in the new year $4.5 billion richer, with an expanding family of funds that has heated up local competition for the investment dollar.

Key acquisitions, an expanded management team and a new-found focus on customer service has helped the Boston-based mutual fund company more than double its assets under management from $3 billion to $7.5 billion.

In 12 months, the subsidiary of John Hancock Life Insurance added The Patriot Group, a Boston-based family of closed-end funds; Sovereign Investors Fund of Berwyn, Pa.; and NM Capital Management, a private account money manager in Albuquerque, N.M. Then, in October, it assimilated Freedom Mutual Funds into its burgeoning product line.

Hancock has embarked on an ambitious strategy to win back market share--and win over critics who blasted the fund company in the late 1980s for being disorganized and slow to respond to client inquiries.

John Hancock Mutual Funds CEO Edward J. Boudreau estimated that Hancock had once captured 1.6 percent of the entire U.S. mutual fund market, but its poor reputation for customer service and an overpriced …