11. Equity

Dividends and Distributions

Our board of directors declared the following dividends in 2016 and 2017:

We have an effective universal shelf registration statement registering the potential offer and sale, from time to time and in one or more offerings, of any combination of our common stock, preferred stock, depositary shares, debt securities, warrants and rights (collectively referred to as the “securities”). We may offer the securities directly, through agents, or to or through underwriters by means of ordinary brokers’ transactions on the NYSE or otherwise at market prices prevailing at the time of sale or at negotiated prices and may include “at the market” (“ATM”) offerings or sales “at the market,” to or through a market maker or into an existing trading market on an exchange or otherwise. We completed the following public offerings and ATM offerings of our common stock in 2016 and 2017:

Awards of Shares of Restricted Common Stock and Restricted Stock Units under our 2013 Plan

Our Board of Directors have authorized 4,452,597 awards for issuance under our 2013 Plan. As of December 31, 2017, we have issued awards with service, performance and market conditions and have 1,635,094 awards remaining available for issuance. In October of 2017, we amended the terms of the performance based restricted stock units granted under the plan to have all unvested restricted stock units vest upon a change in control. During the year ended December 31, 2017, our board of directors awarded employees and directors 710,148 shares of restricted stock and restricted stock units that vest from 2017 to 2021. As of December 31, 2017, as it relates to previously issued restricted stock awards with performance conditions, we have concluded that it is probable that the performance conditions will be met.

A summary of equity-based compensation expense and the fair value of shares vested on the vesting date for the years ended December 31, 2017, 2016, and 2015 is as follows:

The total unrecognized compensation expense related to awards of shares of restricted stock and restricted stock units was approximately $12 million as of December 31, 2017. We expect to recognize compensation expense related to these awards over a weighted-average term of approximately two years. A summary of the unvested shares of restricted common stock that have been issued is as follows:

A summary of the unvested shares of restricted stock units that have market based vesting conditions that have been issued is as follows: