FRANKFURT (Reuters) -German pharma firm Stada plans to launch its initial public offering (IPO) as soon as Wednesday, two people familiar with the matter said, in a test for Europe's equity markets.

The drug manufacturer, majority-owned by private equity firms Bain Capital and Cinven, is preparing to issue an intention to float on the Frankfurt bourse as soon as this week if markets hold up, the people said, speaking on condition of anonymity.

Known for its cold medicine Grippostad, sunscreen Ladival and the cough syrup Silomat, Stada could be valued at around 10 to 12 billion euros ($10.87 billion-$13.05 billion). 

Stada declined to comment. Bain and Cinven declined to comment.

If it goes ahead this week, Stada would be one of the largest IPOs in Europe since last year's float of Spain's Puig, and could make it into the MDax or even DAX company index. 

There is still scope for the launch date to shift, for example if there is market news that impacts the VIX index, a commonly used measure for market volatility, the people cautioned.

If the timeline is adhered to, Stada's return to the stock exchange could be on April 11, but this may also be subject to delay, one of the people said.

Stada wants to generate around 1.5 billion euros ($1.63 billion) in proceeds from the shares sold, this person said. 

Investment banks will begin to formally canvass investors following the intention to float announcement to define a valuation range for the share sale.

Reuters previously reported that Stada aimed to go public at the beginning of the second quarter this year.

Stada recently lined up Andreas Fibig as a new independent chairman in a key step ahead of a listing.

Its owners Bain Capital and Cinven have been preparing for the share sale after talks over a sale to rival financial sponsor firm GTCR stalled, as previously reported.

Bain and Cinven took Stada private in 2017 for 5.3 billion euros ($5.77 billion).

($1 = 0.9178 euros)