Victoria's Secret is missing out on a multibillion dollar opportunity

Victoria's Secret is the most powerful lingerie brand in the world, controlling an estimated 35% of the market.

But the brand could easily drive sales by offering plus sizes.

The plus-size market is worth $9 billion, IBIS World reported in July. Yet, like many other retailers who are missing out on this opportunity, Victoria's Secret doesn't offer larger sizes.

Thousands of people have signed petitions in recent months for Victoria's Secret to offer larger sizes.

The largest panty size it offers is XL, or equivalent to a size 16. The fashion industry defines plus-size clothing as sizes 12 to 24, though many retailers offer up to a size 28 to meet demand.

Bra sizes are inconsistent. Some styles are offered up to a D, while others go up to a DDD.

Still, many women feel they don't have a good selection at Victoria's Secret.

The author of one petition, Dana Drew, says she loves her California Victoria's Secret store so much that she has a credit card there.

She can't, however, buy lingerie there.

"My money and my credit are good enough for them, but the fact that I can only buy items like perfume, lotion, and body spray sends the message that my body is not," Drew says. "Every year I watch the Angel fashion show and would love to purchase the items I see on my screen but can't because Victoria's Secret doesn't sell plus sizes."

Victoria's Secret hires so-called "angels" to be its namesake models (the brand recently hired 10 new stunning women).

These women are known for their svelte physiques.

But the brand might need to consider offering more diverse body types on the runway, Jeetendr Sehdev, professor of marketing at the University of Southern California, told Business Insider.

"At one stage, Victoria's Secret had a very fresh, new perspective," Sehdev said. "Women were very much aware that this is a media ideal of beauty, and they bought into it to a set degree."

Plus-size model Brittany Cordts launched a petition asking Victoria's Secret to hire bigger models.

Cordts, who is a size 14, said she was upset after watching the runway show and seeing small models - especially since the store sells clothing beyond a size 0.

"My petition is to encourage them to send models [that are the same size as the lingerie] that they currently offer ... 4, 6, 8, 10, 12, 14- just so there's diversity, so its not all size zero and two," she said. "If they extend their sizes in the future,great, but right now I'd like to focus on stopping that negative image that they send to all these women and teens."

Further, Cordts told Business Insider she believes Victoria's Secret has a unique opportunity because of its influence.

"There are all these clients that offer plus size and other lingerie brands," Cordts said. "Victoria's Secret is the number one retailer of lingerie in America, and they reach tens of millions of women and teens with their show, and those other brands don't have the reach and impact that Victoria's Secret does."

Victoria's Secret didn't respond to a request for comment.