Prev Close way off?

Question

For quite awhile, I have noticed odd discrepancies between the Prev Close shown on charts (such as Technical Analysis) and what a stock actually closed at on the prior trading day. This appears to be somewhat random, though at one point I thought it had to do with wrongly using "Adj Close" for "Prev Close", when dividends have occured.

Today, I notice DML.to (which has had no dividend) is showing "Prev Close" = "Last Trade". The Close yesterday was actually C$12.25.

Answer 1

There are several inconsistent sites including barchart and yahoo. Just last month, barchart listed the SP droping 82% and BRKA crashing to $10,000 a share (instead of the over $100,000 it really closed at).