When American Express (NYSE:AXP) lost its co-branded card partnership with warehouse retail giant Costco (NASDAQ:COST), it marked a low point for the long-lived financial company. Yet since then, American Express has found ways to recover, and even though other lost partnerships have weighed on the company, investors are optimistic about AmEx's ability to find new avenues for growth. Already, American Express stock has climbed 50% from its lows, and it has recovered most of its lost ground since its highs in 2014. The following three things could help drive further gains for the stock and reward shareholders for their perseverance.

1. Favorable borrowing patterns are lifting AmEx's core business.

At the end of the day, what matters for American Express is how much its customers use the core services it provides. Lately, those figures have been improving. In the first quarter of 2017, AmEx reported a 12% rise in total loan growth after adjusting for currency fluctuations. Much of that gain came from existing AmEx customers, on which the company already has a firm understanding of credit-related behavior and repayment risk. The greater emphasis on existing customers has allowed American Express to save money on marketing costs, and it has also encouraged loyalty among those customers when it comes time to renew their cards.

The same trends have shown up in the card business. When you adjust for the loss of Costco business, cardmember spending climbed 8% from year-ago levels. As AmEx finally puts the Costco event behind it for year-over-year comparison purposes, investors should start seeing a return to more favorable growth numbers overall.

Person paying using American Express.

Image source: American Express.

2. Fee increases will finally start to offset incentive costs.

Earlier this year, American Express announced that it would increase the annual fee on its flagship Platinum card from $450 to $550. The $100 per year increase went into effect on March 30, and it follows other increases on various products recently. For instance, AmEx last year boosted its Blue Cash Preferred annual fee from $75 to $95, and fee increases have been implemented elsewhere as well.

Some fear that these fee increases will scare off customers, but their primary result will be to help offset the rising costs of paying incentives to lure new cardmembers from other cards. For instance, AmEx Platinum offers plenty of valuable features, including $200 in annual Uber credits, $200 toward airline fees, airport lounge access, and various hotel benefits and rewards credits. By being smart about leveraging its highest-profile cards, American Express should be able to compete more effectively with the other companies in the card industry.

3. More shareholder-friendly practices could lift the stock.

Part of what has helped American Express shares over the past year are the company's efforts to return more capital to its shareholders. Last year, it announced that it would boost its dividends and use stock repurchases to get even more money into investors' hands. American Express raised its dividend by 10% in October 2016, and it has also spent more than $4 billion on stock buybacks over the past 12 months, continuing the ramp-up in its repurchase that AmEx started several years ago.

Because of American Express' status as a financial institution, it must get approval from the Federal Reserve for its capital plans. Yet with the company having submitted its requests through the Comprehensive Capital Analysis and Review process at the Fed, AmEx is hopeful that it will be able to continue in its moves to enhance return of shareholder capital at an accelerated rate. With a dividend yield of just 1.6%, the card giant has a long way to go before it can call itself a high-yield dividend stock, but investors are pleased with the efforts thus far.

American Express is making progress, and its stock has already reflected greater enthusiasm for its future plans. Looking forward, there's reason to believe that AmEx can continue to see its stock rise over time, especially if things go well for its core business going forward.