From Sega Retro
Kalisto is a console warez group established in March 1998 which specializes in the release and distribution of Sony PlayStation (PS1) and PlayStation 2 (PS2) ISO images, briefly moonlighting on the Sega Dreamcast platform in mid to late 2000.
Kalisto and the Dreamcast
Kalisto first entered into the Dreamcast scene on June 26, 2000 with the release of the title Evolution: The World of Sacred Device.  By August 19, 2000, Kalisto had determined how to rip and redistribute Dreamcast GD-ROMs as CD-ROM ISOs without the need for a swappable "bootdisk" CD-ROM.  A few weeks later, on September 2, 2000, Kalisto claimed that Sega provided a financial incentive for them to stop releasing games for the Dreamcast platform: 
|“||Sega has offered us stock options to stop releasing DC, so this will be it, our last release. Thanks to all who have supported us throughout our stay in the DC scene. Take note this is NOT a joke. We are really stopping all DC operations with this release. We will continue on with the PSX. Bye.||„|
While the claim of stock options was allegedly a joke , Kalisto ceased all releases for the Dreamcast shortly after and focused entirely on PlayStation games. Immediately after, a new group called Echelon emerged on September 4, 2000, picking up the slack to later become the number one release group for the Dreamcast.  At the time of this transition, there was much speculation that Kalisto and Echelon were one and the same.
In 2004, Kalisto was named as one of six groups targeted as part of Operation Fastlink by the United States Department of Justice.