In an announcement made last Friday, Mexican construction form ICA said it is selling 95 million shares in airport operator Grupo Aeroportuario del Centro Norte to raise about US$375 million. The said shares represent 23.75% stake in OMA which is currently owned by ICA.

The largest infrastructure firm in Mexico had priced the shares at US$3.95 per share. The plan is to raise funds without diminishing ICA's 'significant interest;' in OMA even after the said sale.

This comes after a previous Bloomberg report said that Empresas ICA SAB, ICA's formal name, has filed for shelf registration with the United States Securities and Exchange Commission for the sale of as much as 100 million shares in OMA. The said filing was dated May 15, 2013.

The said filing would allow ICA to sell a portion of its shareholdings in OMA when it deems appropriate. The shares to be sold off would be OMA's Series B shares or American Depositary Shares.

Thus the approval of the said filing resulted in the eventual sale.