Usually considered a bad deal to existing shareholders because PIPE's are generally issued below market value to a group of investors. In other words, if a stock is trading at $10, an investment group could get shares for $7 through a PIPE transaction. Its a way for a company to raise cash.
Around April it started floating around that NMKT had issued a PIPE for $3 million. This was just one issue that was tossed around as being the reason for NMKT's sharp decline.