Shares in Liberbank SA rebounded by more than 20% after Spanish stock market regulator Comisión Nacional del Mercado de Valores, or CNMV, prohibited short-selling on the bank's stocks, Reuters reported June 12.

The CNMV decided to ban short sales of Liberbank's shares and similar transactions for a month until July 12 following sharp falls in the bank's share price even though "no negative informations have been disclosed by the bank." The regulator surmised that the plunge was related to Banco Popular Español SA's takeover by Banco Santander SA.

Liberbank's shares were up 26.3% at 85.9 euro cents at 8 a.m. GMT, erasing a 17.6% drop June 9, according to Reuters. The European Securities and Markets Authority did not object to the ban, the CNMV said.