MetLife Inc said it plans to sell more than $3 billion of stock to help pay for its acquisition of the foreign life insurance business of American International Group, or about 50 percent more than it originally expected.

The company did not comment on why it was boosting its issuance plan. When MetLife announced that it was buying American Life Insurance Co from AIG in March, it said that it was paying AIG $8.7 billion of equity and $6.8 billion of cash.

It planned to generate the cash from selling $3.1 billion of debt and $2 billion of equity, with the rest coming from cash on hand.

The planned equity issuance has now risen to 75 million shares, or more than $3 billion based on Friday's closing price.

Because of the higher share issuance, MetLife Inc lowered its estimate of how much of a per-share boost it will get from acquiring Alico.

MetLife said it now sees operating earnings per share for the year rising 40 cents to 45 cents. The company had previously said it expected to realize a 45 to 55 cent-per-share boost to its 2011 profit.

Analysts expect MetLife to report $5.35 per share for 2011, according to Reuters Estimates.

MetLife said it still plans to sell about $3 billion in senior debt to help pay for Alico.

Last week, MetLife posted second-quarter operating earnings, excluding investment gains and losses, of $1.02 billion, or $1.23 a share, beating analysts' average forecast of $1.00 a share, according to Reuters Estimates.

MetLife also said the Alico purchase will enable it to boost its 2011 year-end operating return on equity by about 1 percentage point.

It said operating earnings per share does not include transition and other one-time expenses estimated at 12 cents per share.

MetLife first started eyeing Alico, which sells life, accident and health insurance as well as retirement and wealth management products in 55 countries, in the months before AIG nearly collapsed in September 2008.

MetLife will get a special boost in Japan, the world's second-largest life insurance market, which accounts for as much as 70 percent of Alico's pretax operating income.

MetLife's shares rose $1 to $43.06 in morning trading on Monday, as the broader market rallied.

(Reporting by Christopher Kaufman and Dan Wilchins, editing by Maureen Bavdek, Dave Zimmerman)