AMTD Digital made its New York debut last month, priced at $7.80 a share. This week, the firm's shares have been on a rollercoaster ride, closing on Wednesday at $1,100. The meteoric rise in AMTD Digital's value has seen it likened by some commentators to "meme stocks", shares that gain popularity among retail investors through social media. Trading in the company's shares has been particularly volatile this week, as its value rose above $300bn on Tuesday. That meant that AMTD Digital briefly overtook technology giant Alibaba's New York stock market valuation. In Wednesday's trade it plunged by more than 30%,…