Stonegate Mortgage plans to raise up to $100 million in an initial public offering, according to documents filed with the Securities and Exchange Commission late last week. Meanwhile, stock prices for other mortgage-related companies that priced IPOs this year have declined. Stonegate is unique among mortgage company IPOs this year in that it’s not a real estate investment trust. Three of the four mortgage-related IPOs that have priced in 2013 have been for REITs and the other was a nonbank affiliated with a REIT. Stonegate was founded...