These are SEC forms. The S-1 is the form that a company files when they are ready to have an IPO. It is several thousand pages long and has everything from seve

These are SEC forms. The S-1 is the form that a company files when they are ready to have an IPO. It is several thousand pages long and has everything from several years of financial statements to market analyses by third parties so investors know what they are buying when they invest in the company. 10-K and 10-Q are the annual and quarterly reports that public companies have to file by law with the SEC. These documents are the baseline of all investment activity. They are not enough for really hardcore investors, but they are a good subset of the material you need to make informed investment decisions. An aside: Typically equity rounds are referred to as Seed (<1 million), Series A, Series B...etc.