Molina Healthcare Inc. said fourth quarter net income rose 30 percent on premium growth from an acquisition and existing operations, plus improved returns on investment income.

After Tuesday’s market close, the Long Beach-based health maintenance organization operator reported quarterly net income of $11.6 million, or 41 cents per diluted share, compared with $10.7 million (38 cents) for the same period a year ago. Revenue increased 30 percent to $549.5 million. Wall Street expected a quarterly profit of 41 cents per share on $540.6 million revenue, according to an analyst poll by Thomson Financial.

Molina last May acquired of Cape Health Plan in Michigan, which contributed $46.8 million in quarterly revenue. Investment income rose 65 percent to $5.6 million pm higher invested balances and rates of return.

Full fiscal year net income increased 66 percent to $45.7 million ($1.62). Molina Healthcare’s membership grew to 1.1 million as of Dec. 31, compared to 893,000 the prior year. Molina reiterated guidance for earnings per share in fiscal 2007 of $1.75 to $1.90. Analysts are expecting per-share income of $1.81.

Prior to the earnings release, Molina shares gained 51 cents to close at $30.28 on the New York Stock Exchange. Shares fell 3 cents in after-hours trading.