UPDATE 3-Chair of Sweden's top pension firm resigns after dud investments

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COPENHAGEN, Oct 2 (Reuters) - The chair of the board of Alecta, Sweden's largest pension fund provider, resigned on Monday following months of questions over the company's loss-making investments in U.S. banks and a Swedish property group.

Alecta, the subject of two ongoing probes by the Swedish Financial Supervisory Authority (FSA) over risk taking, said in a statement its deputy board chair, Jan-Olof Jacke, will lead the board until a permanent candidate is elected.

"In a situation where there has been too much focus on my person, I have decided to resign," Ingrid Bonde said in a statement.

Alecta's board in April fired its CEO, and the FSA launched a probe, after it lost 19.6 billion Swedish crowns ($1.78 billion) from holdings in U.S. lenders First Republic Bank, Silicon Valley Bank and Signature Bank as those collapsed.

Alecta's asset management chief stepped down shortly after.

Last month the FSA launched a second probe, this time into whether Alecta complied with regulations when it invested 50 billion crowns in Swedish property company Heimstaden Bostad.

"The Financial Supervisory Authority's review of how Alecta handled the investments continues. Alecta's focus or orientation does not change because Ingrid Bonde chooses to resign," the company said.

Sweden is one of Europe's wealthiest states and the biggest Nordic economy, but it has an Achilles Heel - a property market where banks have lent more than 4 trillion Swedish crowns ($360 billion) to homeowners.

That property crisis accelerated last month when pension fund Alecta, which owns a 38% stake in Heimstaden Bostad, said Sweden's biggest residential landlord needed cash and it may contribute.

Swedbank estimated the shortfall for Heimstaden Bostad could be roughly 30 billion crowns ($2.7 billion).

That prompted the inquiry into why and how Alecta had invested $4.5 billion in the property giant in the first place. Its troubled investment accounts for 4% of its funds. (Reporting by Terje Solsvik, editing by Louise Breusch Rasmussen and Christina Fincher)