Is it possible to get historical market capitalization data via the quantmod package?
Updated:
Given Yahoo for example only provide market cap as of today, i wonder is it ok to try infer historical market caps by:
[market_cap_today]/[adjusted_price] = [share_volume]
And then use [share_volume] to get the market cap for last week via:
[share_volume]*[adjusted_price_last_week] = [market_cap_last_week]
The quantmod package can only provide access to data if external data providers make it available. I don't believe Yahoo Finance, Google Finance, etc provide historical market capitalization, so the answer to your question is "no".