(Adds)

COPENHAGEN, Oct 3 (Reuters) - The CEO of Novo Holdings, the controlling shareholder in drugmaker Novo Nordisk , said on Tuesday he sees the window for initial public offerings (IPOs) opening within 18 months and is encouraging portfolio companies to get ready.

Novo Holdings' CEO Kasim Kutay made the remarks while speaking to a group of journalists at the investment company's headquarters in Copenhagen.

Novo Holdings holds 28.1% of economic (or A) shares and 76.9% of voting (or B) shares in the Denmark's Novo Nordisk.

Novo, the drugmaker, is riding a wave of record profits from its new weight-loss and diabetes drugs, Wegovy and Ozempic. Its share price has roughly tripled over the past four years.

As a result, its controlling shareholder, the Novo Nordisk Foundation, is coming into a big windfall.

According to Berenberg analysts and Reuters calculations, the Foundation will receive about $12.5 billion in returns between last year and 2026. That is roughly double what it received over the years 2018-2021 before Wegovy launched in the U.S.

Holdings has 161 portfolio companies, which don't reflect the full investment activities, Kutay said, given the investments through external portfolio managers and funds into other companies.

The roughly 50-50 split between life sciences and capital investments makes sense for Novo Holdings because the sector is embedded in the broader Novo Nordisk Foundation structure, Kutay said.

"We are differentiated because we know it well and can make a difference," he said, adding that the healthcare sector more broadly has "incredible tailwinds" and will continue to grow due to ageing populations, chronic diseases including obesity, and large investments in healthcare by governments in emerging markets.

Kutay said Holdings had 160 employees as of June but is looking to grow to 180 next year. It has six offices globally, including one opened in Shanghai earlier this year, to focus on investments in China, one in Singapore opened several years ago, and in the U.S., in Boston and San Francisco.

(Reporting by Maggie Fick, Editing by Louise Heavens)