Israeli tycoon Yitzhak Tshuva has become a substantial shareholder in

Formula Systems

(Nasdaq:FORTY). He acquired the Formula shares via his fully-owned company Hasharon.

In Israel, a substantial shareholder is defined as owning 5% or more of a company's equity. Substantial shareholder are required by law to report all transactions in the stock to the Tel Aviv Stock Exchange.

Tshuva may well have been a minor shareholder in Formula, which is controlled by Dan Goldstein and Gad Goldstein, for weeks. But he increased his interest to become a substantial shareholder in the last few days.

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Formula's market cap has dropped from a peak of $900 million to $290 million. Tshuva's interest in the company is worth NIS 55 million

Tshuva has a history of surprising the market. He did it twice this week alone, and the week is only half over. Today he revealed the Formula stake. On Monday his Delek group announced the purchase of a $23 million executive jet.

Tshuva took over the Delek group in February 1998. Until then it was controlled by the TASE-traded

Discount Investments

.

The versatile tycoon also burst into venture capital via his Tel Aviv-traded company Green Venture Capital. He also dived into exploring for offshore oil and gas, buying hefty stakes in Tel Aviv-traded oil companies Avner Oil & Gas and Delek Drilling - shortly before they announced major finds.