Amazon U.S. May bestsellers and general Amazon-based discussion

[Swordmasterman]

Shadow1980 said:

Here's today's update for the monthly rankings for May:

PS4 CoD bundle: #19 (↓2)
XBO Gears bundle: #68 (↑29)
PS Vita: #87 (re-entry)
PS4 standalone: #88 (↓12)
XBO Name Your Game bundle: #93 (↓10)


And here's the initial Week 1 rankings:

PS4 CoD bundle: #21
XBO Gears bundle: #49
PS Vita: #76

Surprisingly strong start for the month for the XBO, considering how poorly it's placed for the past few weeks.

EDIT: Forgot today was Thursday. Here's my weekly update to the yearly rankings:

PS4 CoD bundle: #15 (—)
XBO Gears bundle: #46 (—)
New 3DS XL: #88 (—)

No movement from last week.

Why monthly and weekly ranks have different numbers if we are in the first week of the month ?  the numbers should not be the same ?