TOKYO, Japan: SoftBank's shares fell as much as 10 percent on November 12 after it sold its US$5.8 billion stake in Nvidia, highlighting the massive funding needs it faces for its major bet on ChatGPT maker OpenAI and other tech investments.

The Japanese conglomerate is planning a $22.5 billion follow-up investment in OpenAI, is buying chipmaker Ampere for $6.5 billion, and has agreed to purchase the robotics unit of Swiss company ABB for $5.4 billion.

Analyst Mary Pollock of CreditSights estimates that SoftBank has already committed at least $41 billion in recent deals and investments. The company had 4.2 trillion yen ($27.9 billion) in cash at the end of September. Pollock said SoftBank's cash needs this quarter are "substantial" and that it must be "proactive" in finding new funding sources.

The share drop also reflects investor worries that tech valuations have risen too quickly, even as SoftBank continues to increase its exposure to artificial intelligence.

SoftBank said on November 11 that it had sold its Nvidia stake and also sold $9.2 billion worth of T-Mobile US shares between June and September.

SoftBank's founder and CEO, Masayoshi Son, known for his bold and risky investments, remains optimistic about AI's potential.

Rolf Bulk, an analyst at New Street Research, said SoftBank's sale of Nvidia shares doesn't mean it has lost confidence in the company. "The position was large and easy to sell, and SoftBank likely sees more upside in investing that money into OpenAI," he said.

In June, Son compared today's AI leaders to companies like Google and Amazon, saying that strong firms will continue to grow and dominate over time.

SoftBank's stock had more than quadrupled between April and October, but it has fallen in recent days. On November 12, shares recovered slightly, closing down 3.46 percent. Nvidia and Arm — the chip designer controlled by SoftBank — each fell about 3 percent overnight.

To support its heavy investments, SoftBank has been selling shares, issuing bonds, and taking loans. It secured an $8.5 billion loan to fund its OpenAI investment and arranged a $6.5 billion bridge loan for the Ampere deal, which it hasn't yet used.

Since April, SoftBank has also issued bonds worth 620 billion yen ($4.1 billion), $2.2 billion, and 1.7 billion euros ($2 billion).

SoftBank's loan-to-value ratio — a measure of debt levels — stood at 16.5 percent at the end of September, down slightly from the previous quarter. However, CFO Yoshimitsu Goto said that level was "actually a bit too safe."

Despite concerns that tech stocks are overpriced, Navneet Govil, CFO of SoftBank's Vision Fund, said demand for AI services supports the fund's strategy.

"What's different from the dot-com boom," he told Reuters, "is that AI companies are already generating real revenues. The big spending we're seeing now is driven by actual demand."