Spread Pricing Liquidity Act of 2013 - Amends the Securities Exchange Act of 1934 concerning the national market system for securities to authorize the board of directors of an issuer with a public float of $500 million or less to select to have the issuer's securities quoted and traded using an increment (tick) of either $0.05 or $0.10.

Prohibits selection of the $0.05 tick unless the average trading price in the most recent 1-month period for the securities of an issuer is between $1 and $2. Limits the tick selection to $0.05 for the issuer of any such security.

Prescribes trading requirements. Permits a issuer that has made the selection under this Act to choose to opt out at any time after the six-month period beginning on the date the selection was made.

States that, if the public float of an issuer that has made such a tick selection rises above $500 million (based on a rolling average over the course of a 3-month period), or its average daily trading volume rises above $500 million, then after the end of the 3-month period beginning on the date of such occurrence the issuer: (1) shall no longer be considered to have made the tick selection; and (2) shall be ineligible to make such a tick selection for 2 years after such 3-month period.

Directs the Securities and Exchange Commission (SEC) to study the quoting and trading of securities in increments of $0.05 and $0.10, and the extent to which such system increases liquidity by incentivizing capital commitment, research coverage, and brokerage support.