Spotify is said to be advancing in an effort to raise another $500 million — and possibly $1 billion — for its war chest. A report at Sky News says the digital service is in talks with private equity firm TPG Capital for $500 million in convertible debt financing and could raise the funding round as high as $1 billion.

This latest report puts TPG’s name on a report in late January that Spotify had engaged itself in another funding round. The report doesn’t come as a surprise. Spotify has rarely not been seeking funding since 2008. It has raised over $1 billion from the likes of Goldman Sachs, Accel Venture Partners and Sean Parker‘s Founders Fund.

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The size and frequency of the funding arounds say a lot of investors’ sentiment. As is typical with large, fast-growing tech companies, Spotify’s funding rounds have become larger as the company has proven its leadership position and ability to benefit from consumers’ shift from purchases to subscriptions. The company raised $500 million in June, $250 million in November 2013 and $100 million in November 2012.

The type of funding is also a signal of Spotify’s maturity. Large, institutional investors tend to invest in fast-growing tech companies when their growth and market share has reduced the risk of not getting a return on investment. Debt-to-equity funding is also common with late-stage investors that want to get their money out first — debt gets preferential treatment to equity — or choose to convert the debt to equity to capture the upside in an acquisition or initial public stock offering. Another benefit to investors is the fact that debt-to-equity doesn’t require a company valuation at the time of investment. In contrast, equity investments take a share of the company for a specified price.

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Why invest in Spotify? The company is said to be nearing 30 million subscribers worldwide and has over 75 million monthly users. It currently has one serious competitor in Apple Music and other, smaller competitors with less market share and less momentum. And even though Apple Music is growing and Pandora will soon launch a similar service, subscriptions might be a large enough market for two or three main services — although Spotify’s investors are no doubt hoping Apple Music and Pandora will be a distant second and third.