(MONEY Magazine) – The vitality of America's mid-size companies is one of this country's better- kept secrets. Reason: Securities analysts generally concentrate either on multibillion-dollar behemoths or small, --ashy growth companies. So investors don't hear about many great, but unobtrusive, buying opportunities. Take these two midcap stocks. They could gain at least 30% over the next 18 months, but -- thanks to investor neglect -- they trade at less than 14 times projected 1995 earnings. Caldor (symbol: CLD; NYSE, $29.75; no yield). With annual revenues of $2.8 billion, this regional discount retailer is a pipsqueak compared with its national rivals, $37 billion K Mart and $86 billion Wal-Mart. Nonetheless, Caldor's profits could increase about 15% a year, says analyst Michael Exstein at Kidder Peabody. Reason: Caldor began '94 with 150 stores and is adding 15 a year, for a 10%-plus annual increase in selling space. The chain also has carved out a niche for itself in urban and inner-suburban locations, says analyst Bernard Sosnick at Oppenheimer & Co. in New York City. "Urban stores have high sales per square foot," he says, "but even though the market is underserved, competitors can't come in easily because there aren't a lot of urban sites available." The company was taken private in a $537 million leveraged buy-out in 1989 and then went public again in 1991 at $21 a share. Sosnick believes that the stock could climb as much as 34% to $40 over the next 18 months. King World Productions (KWP; NYSE, $37.75; no yield). Television production companies are generally risky, but this $531 million firm is a model of financial solidity. "Their long-term contracts guarantee that they will bring in $1 billion of operating profits over the next five years," says analyst Lee | Isgur at Volpe Welty in San Francisco. "Further, they have more than $400 million in cash and no debt." About one-third of the company's profits come from syndicating the Oprah Winfrey Show nationwide, and Ms. Winfrey renewed her contract in March. "The signing eliminates a major risk for the next several years," says Jessica Reif at Oppenheimer & Co. in New York City. King World also distributes game shows Wheel of Fortune and Jeopardy and owns and distributes the television tabloid news shows Inside Edition and American Journal. In addition, the company owns the Little Rascals movie shorts made between 1922 and '44. "Those episodes will be more valuable now that Steven Spielberg is making a movie version of the series," says Isgur. He notes that earnings growth could fluctuate from quarter to quarter because of accounting practices standard in television production companies, but both analysts think the shares could be up 32% to $50 over the next 18 months.