There's a difference if you DCA a broad index and a single thing. The broad index will, most likely, be positively skewed and still be around in 20 years. DCA

There's a difference if you DCA a broad index and a single thing. The broad index will, most likely, be positively skewed and still be around in 20 years. DCA makes a lot of sense. The single stock may just go bankrupt, or become smaller and never recover (think Kodak or Nokia). DCA does not make as much sense.