Bitcoin and gold rallied this week as the size of America’s sovereign debt continued to haunt global financial markets. Meanwhile, Alibaba Group Holding’s top executives and founder Jack Ma bought back shares, and Shein announced plans for a smaller Hong Kong initial public offering than previously expected.Here are some of the figures that have drawn the most market attention this week.Founder, executives buy over HK$800m of Alibaba sharesAlibaba founder Ma, chairman Joe Tsai and CEO Eddie Wu Yongming collectively bought more than HK$800 million (US$102 million) worth of the company’s Hong Kong-listed shares within days.Ma accounted for more than HK$600 million of the purchases, while Tsai and Wu spent a combined HK$202 million, signalling confidence in Alibaba – owner of the South China Morning Post – as it steps up its push into artificial intelligence.Bitcoin climbs above US$80,000