After Microsoft Co-Founder Bill Gates made a bet on Spain-based FCC three months ago, billionaire George Soros followed suit and bought a stake in the indebted construction firm, the Financial Times reported. Citing people familiar with the transaction, the report said funds associated with the philanthropist, who earned his reputation by making billions speculating in currency, purchased a 3.1% stake in the firm from Esther Koplowitz last week. Koplowitz is a philanthropist and the largest shareholder of the FCC.

One of the richest women in Spain, Koplowitz divested a 3.8% stake in the Spanish builder valued at €72 million through Fidentis, a Spanish broker, last month, according to a stock market filing by the FCC. She held on to a little over 50% of its shares. FCC did not reveal who the buyers were.

FT reported that any investment made in a Spanish firm that is valued over 3% of its available share capital need to be declared. However, since the Soros investment was made partly through derivatives, it was able to avoid declaration, the report said.

When the decade-long property boom in Spain went bust, some of the country's biggest construction firms were forced to near insolvency after years of accumulating debt for their expansion projects. With the Spanish economy showing signs of recovery in the past few months, investors have started to identify these firms as possible investments, the report said.

In October, funds linked to Bill Gates bought a 6% stake in FCC valued at €113.5 million, fueling an increase in the firm's share price. The market looked at the move as a sign of increasing confidence in the economy of Spain. The share price of FCC has increased 125.4% in the past six months. The report said the construction firm has sold assets and concentrated on growing its business outside of Spain in order to reduce its large debts.