What: Shares of American Equity Investment Life Holding Company (NYSE:AEL) plunged by nearly 17% as of 12:15 p.m. EST Wednesday on news the Department of Labor is cracking down on indexed annuities.

So what: The Department of Labor is changing the retirement game, hoping to force brokers and financial planners into working as fiduciaries for their clients. The central goal is to improve the alignment of interests between planners, who have an incentive to push clients into high-fee products, and their clients.

American Equity Investment Life Holding Company is one of the largest sellers of indexed annuities. Under the new rules, conflicts of interests between brokers and annuity buyers will have to be disclosed to the customer, which could put a dent in indexed annuity sales.

Now what: From asset management companies to banking stocks, most financial stocks had already adjusted to the market's expectations about how the Department of Labor's new rules would affect sales of investment products. Importantly, however, it was largely thought that index annuities would be excluded.