&& Snapchat has filed for an initial public offering, sources familiar with the situation said on Tuesday, which puts the messaging app a step closer to the biggest U.S. stock market debut since 2014. The Venice, California-based company could go public as soon as March and be valued at $20 billion to $25 billion, making it the largest IPO since Chinese e-commerce giant Alibaba Group Holding Ltd’s went public two years ago valued at $170.9 billion. It would be the largest U.S. technology IPO since Facebook Inc’s debut in 2012 with a value of $81.2 billion.