The practice was known as “zaitech”
> zaitech - financial engineering
> In 1984, Japan’s Ministry of Finance permitted companies to operate special accounts for their shareholdings, known as tokkin accounts. These accounts allowed companies to trade securities without paying capital gains tax on their profits.
> At the same time, Japanese companies were allowed to access the Eurobond market in London. Companies issued warrant bonds, a combination of traditional corporate bonds with an option (the “warrant") to purchase shares in the company at a specified price before expiry. Since Japanese shares were rising, the warrants became more valuable, allowing companies to issue bonds with low-interest payments.
> The companies, in turn, placed the money they raised into their tokkin accounts that invested in the stock market. Note the circularity: companies raised money by selling warrants that relied on increasing stock prices, which was used to buy more shares, thus increasing their gains from investing in the stock market.
https://www.capitalmind.in/insights/lost-decades-japan-1980s...