Wall Street will be busy after Labor Day with what could be the biggest IPO in U.S. history and Apple’s launch of the iPhone 6. Alibaba’s roadshow for its initial public offering will begin shortly after the summer’s final holiday, kicking off in Hong Kong and Toyko before moving to London and New York. Some reports indicate the IPO could hit the New York Stock Exchange on September 16. Given the expected size of Alibaba’s offering, the NYSE will be doing test runs at the beginning of September. Alibaba’s offering will also have a direct impact on Yahoo’s stock given its over 20% stake. Jim Cramer believes the listing may also pull some investors from e-commerce firms as large as Amazon. Apple will provide Alibaba stiff competition for headlines. The iPhone maker has sent out invites to a Sept. 9 event where it is expected CEO Tim Cook will unveil the iPhone 6. Apple believes it has one of the company’s strongest-ever product pipelines, and fanboys expect the launch of a wearable product. Merger mania continues to grip Wall Street. While it won’t be a surprise if some large new deals come out immediately after the holiday, there is also a big pipeline of pending deals. Investors continue to watch whether wireless carrier T-Mobile will go at it alone. Antitrust remains a major issue for investors holding stock in many of 2014’s biggest deals such as the proposed mergers of AT&T and DirecTV, Comcast and Time Warner Cable, and Sysco and U.S. Foods.