Korean chipmaker SK hynix is estimated to have purchased about 20 trillion won ($13.2 billion) worth of bonds this year as record earnings from the booming chip industry swelled its cash holdings, industry sources said Wednesday. The chip giant's purchases span a broad range of high-grade credit products, including bonds issued by Korea Electric Power Corp., other public institutions, banks, financial firms, securities companies and specialized credit finance companies, the sources said. Industry observers said SK hynix has emerged as one of the largest investors in the domestic credit market as its record-breaking semiconductor earnings have sharply boosted its cash holdings, creating a need for short-term investment vehicles to manage excess liquidity. SK hynix posted record first-quarter earnings, reporting 52 trillion won in revenue and 37 trillion won in operating profit. Its cash and cash equivalents totaled 54.3 trillion won at the end of the January-March period, up 19.4 trillion won from three months earlier. Reflecting its strong earnings momentum, SK hynix shares have surged mo