* Citigroup will keep most insurance risk

* Primerica shares will be used as incentive for sales staff (Adds byline; Primerica's book value, history)

By Dan Wilchins

NEW YORK, Nov 5 (Reuters) - Citigroup Inc (C.N: Quote, Profile, Research) said on Thursday it plans to raise up to $100 million through selling shares of its Primerica Inc life insurance unit, as the financial colossus looks to shed assets outside its main banking business.

Citigroup tried earlier this year to sell the whole of Primerica, a life insurer that specializes in door-to-door sales, but failed to find a buyer willing to pay enough.

Most of Primerica's insurance risk from policies sold through the end of this year will be kept by Citigroup, according to Primerica's registration statement.

Citigroup has not yet determined the percentage of Primerica that it is selling. The $100 million value for the sale may be increased if demand is strong enough. Citigroup hopes to sell the rest of Primerica as soon as possible.

Primerica's accounting value overall, as measured by the book value of its equity, was $4.6 billion as of the end of June. But most of that value is from its insurance policies, which will by and large not be part of the initial public offering.

The IPO will help Primerica offer shares to its sales staff as an incentive, the company's registration statement said. Shares will be given to some Primerica employees and sales force leaders alongside the offering, and the unit plans to create a Primerica equity award compensation program.