There are three different types of DRIPs - DRIP directly run by the concerned companies, DRP through transfer agents and DRP arranged by brokers.
Many companies directly organize DRIPs on their own without any external support in a bid to build healthy shareholder relationship. These DRPs can be bought directly from the company – sometimes even by persons not holding a single share of the company.
Then there are the transfer agent-run DRIPs. Many companies find managing DRPs far too tedious and opt for outsourcing the work to Transfer Agents. Most transfer agents are well-known financial institutions that manage DRP programs for several client companies.
Some brokerage firms assist shareholders to reinvest dividends earned even companies that do not have a formal DRP program. The only limitation to broker-run DRPs is it can apply to dividends alone and not open cash purchases which are referred to as optional cash purchases.