Our marketable securities consist of investments in the publicly-traded shares of our immediate parent company Valhi, Inc. All of our marketable securities are accounted for as available-for-sale securities, which are carried at fair value using quoted market prices in active markets for each marketable security. Any unrealized gains or losses on the securities are recognized in Marketable equity securities on our Condensed Consolidated Statements of Income. The fair value of our equity securities represent a Level 1 input within the fair value hierarchy.

	Fair value measurement level	Market value		Cost basis		Unrealized gain (loss)
		(In thousands)
December 31, 2018
Valhi common stock	1	$	27,740	$	24,347	$	3,393

March 31, 2019
Valhi common stock	1	$	33,202	$	24,347	$	8,855

At December 31, 2018 and March 31, 2019, we held approximately 14.4 million shares of common stock of Valhi. See Note 1. Our shares of Valhi common stock are carried at fair value based on quoted market prices, representing a Level 1 input within the fair value hierarchy. At December 31, 2018 and March 31, 2019, the quoted per share market price of Valhi common stock was $1.93 and $2.31, respectively.

The Valhi common stock we own is subject to the restrictions on resale pursuant to certain provisions of the SEC Rule 144. In addition, as a majority-owned subsidiary of Valhi, we cannot vote our shares of Valhi common stock under Delaware General Corporation Law, but we do receive dividends from Valhi on these shares, when declared and paid.

In March 2019, Valhi filed a Form S-3 registration statement with the SEC, registering our shares of Valhi common stock for resale. The registration statement has been declared effective by the SEC. We may sell all or a portion of such shares from time to time directly or through one or more underwriters, broker-dealers or agents. If the shares are sold through underwriters or broker-dealers, we would be responsible for underwriting discounts or commissions or agents’ commissions. The shares may be sold in one or more transactions at fixed prices, prevailing market prices determined at the time of the sale, varying prices determined at the time of sale or negotiated prices (in each case we may determine). We have agreed to reimburse Valhi for its expenses incurred in connection with such registration statement (which expenses are not material). Through May 9, 2019, we have not sold any of our shares of Valhi common stock under the registration statement.