How can I calculate market share of a particular firm in stata,

[lao wu]

How can I calculate market share of a particular firm in stata, I have 15 Industries and each industry has more than 25 firms

[Carlo Lazzaro]

Lao:
too broad questions seldom usually receive few/no replies.
Please provide the list with more details about your query: help others help yourself! Thanks.

[Phil Bromiley]

You need to follow Carlo's suggestion and the FAQ on asking questions - provide Stata code in code delimiters, readable Stata output, and sample data using dataex.
This may be what you want:

bysort industry: egen totalsales=total(sales),
g mktshare=sales/totalsales