Last Sunday, off-price retail giant TJX (TJX 0.83%) completed its acquisition of Australian off-price retailer Trade Secret.

Considering TJX's massive size -- it produced $30 billion of revenue and nearly $3 billion of operating cash flow in the past 12 months -- this wasn't a very big acquisition, with a total purchase price of less than $60 million. (All currency figures are in U.S. dollars.) However, by opening a new market for growth, this deal represents a significant opportunity for the company.

TJX is a growth machine
TJX has been growing relentlessly for the past five years, adding about $2 billion a year to its top line through a combination of store openings and comparable-store sales growth. TJX ended its most recent fiscal year with nearly 3,400 stores worldwide.

TJX already operates thousands of stores across the world. Photo: The Motley Fool.

The company sees ample growth opportunities ahead. According to its most recent estimate, TJX could eventually grow to at least 5,475 stores just with its current nameplates and markets. That would be up more than 60% from January 2015.

However, TJX is starting to approach market saturation in its "Marmaxx" business segment, which includes the Marshalls and T.J. Maxx chains in the United States. As Marmaxx has gotten closer to its estimated market opportunity of 3,000 stores -- it had 2,120 at the beginning of August -- its growth rate has inexorably slowed. That's problematic, insofar as the Marmaxx segment accounted for 64% of TJX's total sales last year.

If TJX wants to continue growing at a mid-high-single-digit rate, it needs to develop new expansion opportunities. Canada has been a great growth market for many years, but that market also is approaching saturation. The HomeGoods chain in the U.S. has been the most promising growth driver lately, but the TJX Europe segment has been gaining momentum, too.

Australia is ripe for expansion
In the press release announcing the Trade Secret acquisition, TJX CEO Carol Meyrowitz drew a parallel between the Australian and Canadian markets. Trade Secret already has more than $100 million in annual revenue from its 35 stores. TJX's massive scale and global buying organization should enable Trade Secret to accelerate its growth in Australia.

TJX has had huge success in Canada since buying the Winners chain in 1990. Photo: The Motley Fool.

In Canada, TJX has nearly $3 billion in annual revenue today. It sees the potential to expand its store base there by more than 35%. Even adjusting for Australia's somewhat smaller size, it appears that there is a multibillion-dollar revenue opportunity there that TJX can pursue over the next couple of decades.

Nurturing growth seeds
Australia isn't going to singlehandedly replace the growth that TJX has traditionally gotten from the T.J. Maxx and Marshalls chains in the United States. However, as one of many growth seeds for the company, it can play an important role in sustaining TJX's long-term growth.

In the past couple of years, TJX has piloted a fourth retail concept in the United States: the outdoor-oriented Sierra Trading Post. It has only a handful of physical locations so far, but the early stores have performed well, suggesting that there could be an opportunity here.

TJX also took its first steps into two new European markets -- Austria and the Netherlands -- in 2015. Longer-term, the company is likely to expand into more countries in Europe. (Today, it also operates in Germany, Poland, Ireland, and the UK.)

The more new areas TJX can find to support future growth, the brighter its long-term prospects. Its move into the Australian market through the acquisition of Trade Secret seems like a promising lead.