SoftBank reportedly bought billions worth of high-flying tech stocks, helping propel the market's recent record rally

• Japan's SoftBank Group Corp. bought $4 billion of shares in tech companies and another $4 billion of call options tied to roughly $50 billion in tech stocks, according to a report from The Wall Street Journal.
• Regulatory filings showed Softbank's tech-stock buying activity, but did not show the options purchase.
• Softbank sold the call options at a higher price, according to The Journal's report.

• Visit Business Insider's homepage for more stories.

Japan's SoftBank Group Corp. bought and sold options for individual tech stocks worth billions of dollars, which helped propel the tech sector and broader market rally, according to a report from The Wall Street Journal.

According to regulatory filings, the Japan-based multinational conglomerate bought roughly $4 billion of shares in tech giants like Amazon, Microsoft, and Netflix this spring.

Read more: A fund manager at a $629 billion firm lays out his strategy for 'making money at the expense of machines' during the stock market's sell-off — and shares 4 sectors he's betting on

The filings do not mention, however, that SoftBank also spent roughly $4 billion on call options for the tech companies it previously bought, and other names as well. Those options were tied to roughly $50 billion in tech stocks, The Journal reported.

SoftBank sold the call options at higher prices, according to The Journal's report.

The Journal reported that investors have been aware of the recent options activity, but did not know who was responsible for it.

Read more: 'I had run $5,000 up to $140,000 in just 2 years': Here are the 7 trading rules stock-market wizard Marty Schwartz leverages to help ensure success