The Massachusetts Democrat sent a letter Tuesday to units of New York's MetLife Inc. and
Warren said in a statement that the perks include cruises, cash, iPads and Super Bowl-style diamond-encrusted rings and often appear to be "kickbacks" to sales personnel.
"Annuities agents that are more interested in earning perks than in acting in their clients' best interest can place Americans' savings and retirement security at risk," Warren said.
The probe comes as a fight looms over new rules proposed by the Labor Department that would require financial professionals to put clients' interests ahead of their own in selling a broader range of retirement products.
The financial-services industry has opposed a change to the rules, saying the broad imposition of a so-called fiduciary standard for financial professionals could limit access to financial planners, particularly for low- and middle-income retirees.
An annuity is a contract with an insurer designed to provide a steady stream of income in retirement. Customers either make a lump-sum payment or a series of payments, which the insurer then invests in return for a promise of future income. Consumer groups have criticized some annuities for their complexity and high fees.
In her letter, Warren said a preliminary review by her staff revealed a "vast range of perks" that could represent a conflict of interest and might result in sales personnel "providing inadequate advice about annuities to investors and selling products that may not meet the retirement investment needs of their buyers."
Representatives of MetLife, AIG and Pacific Life either declined to comment or couldn't be immediately reached. A spokesman for the industry's major trade group, the American Council of Life Insurers, based in Washington, also couldn't be immediately reached.
Warren, a member of the powerful Senate Banking Committee, wrote that the securities industry in 2003 ended noncash compensation that could pose conflicts for brokers and dealers involved in stock and bond sales.
More than $235 billion in annuities are sold annually in the U.S. through a network of individual agents and advisors. Warren said the agents and advisors work through middlemen known as sales and marketing organizations that act as distributors and wholesalers of the products that are managed by annuities carriers, usually insurers.
Warren said insurers provide perks on annuities sales both to individual agents and the wholesalers. Among the rewards she cited was a trip to Oahu for agents with $165,000 in sales and a trip to South Africa for agents with $420,000 in sales.
The letter seeks, among other things, disclosure of all annuities sales, incentives and disclosure policies for consumers.