Intel regularly cuts prices once a quarter. Typically the prices are cut in Jan/Feb, May, July/Aug, and Oct. These dates are announced well in advance (for a long time you could even see the date on Intel's own website well in advance). Intel follows a regular pattern when cutting prices: each processor moves down one rung on the pricing ladder (in the rare case when 2 new processors were released that quarter, then they move two rungs down). Thus "rumors" float around that are always quite accurate as to the date and amount of Intel price cuts.
AMD does not follow regular price cutting patterns. AMD does not announce ahead of time when the price cuts will be made. In fact AMD often cuts prices weeks before they even announce the official price cuts. As far as I can tell there is no pattern to how much the prices are cut. Thus there aren't "rumors" of the date and amount of AMD price cuts.
The best I can say is that AMD typically (but not always) cuts prices within 3 weeks (either way) of Intel. AMD's price cuts are often (but not always) about the same magnitude as Intel.
AMD is very responsive to market conditions. When the economy was booming in the late 1990s and early 2000 AMDs top chip cost $1299. When the economy was in a recession in 2001/2002, AMDs top chip cost as low as $241. Intel is rigid and fixed with processor price. The top P4 (excluding the P4EE) has been $637 for years (since shortly after its release) regardless of economy or processor performance.