Zara store in Barcelona
People walk past a Zara store in BarcelonaReuters

The net worth of Spanish billionaire Amancio Ortega rose by a whopping $2.3bn (£1.5bn, €2bn) on 23 June, according to the Bloomberg Billionaire Index.

The Spanish billionaire's single-day gain was $500m more than the combined increase recorded by the world's 10 richest people tracked by the index.

Leading to the large gain, shares in Spain-based Inditex, the Zara owner and world's largest clothing retailer, rose 3.9% on 23 June. Ortega, the richest person in Europe and the second-richest in the world, owns 59% of Inditex, which operates more than 6,600 stores and had revenues of €18.1bn in the year ended January 2015.

Inditex has recently experienced strong growth, and the company is planning to open up 480 more stores in 2015.

In addition to the Inditex stake, he has investments in office and retail properties throughout Europe and the US, via two closely-held investment vehicles.

During the first half of 2015, Ortega's fortune increased by $11bn to $72bn. Over the last three years, his net worth increased by 80%.

Ortega has recently overtaken Warren Buffett as the world's second-richest person on a real-time basis.

He has a net worth of $72.4bn at present, below Bill Gates' fortune amounting to $86.1bn, according to Bloomberg. Forbes calculates Ortega's net worth at $74.4bn, still below Gates' $79.7bn.