NEW YORK (AP) — It could become the longest bull market ever ... perhaps with an asterisk.

S&P Dow Jones Indices, which compiles the benchmark S&P 500 index, and other research firms say the current bull market that began on March 9, 2009, is on track to become the longest in history on Wednesday, at 3,453 days.

Other market analysts say not so fast. They say this bull market would have to run until June 2021 to set the record, claiming the longest bull market ran 4,494 days between 1987 and 2000.

The debate centers around whether a downturn in 1990 should be considered a bear market — generally accepted by stock market geeks to be a 20 percent decline from a previous high. It also involves the familiar mathematical concept of rounding.