Here are the biggest percentage gainers and losers in pre-market trading among companies with a market cap between $50 million and $750 million:

Biggest percentage gainers:

• Encore Wire Corp. (Nasdaq:WIRE), up 20% after swinging to a first-quarter profit that substantially beat the Street.

• Spartan Motors Inc. (Nasdaq:SPAR), up 15% on first-quarter earnings and revenue that substantially beat the Street.

• Pozen, Inc. (Nasdaq:POZN), up 8%.

Biggest percentage losers:

• Monarch Casino & Resort, Inc. (Nasdaq:MCRI), down 11% after reporting first-quarter results that declined from the year-ago period and missed analysts’ estimates.

• L.B. Foster Company (Nasdaq:FSTR), down 9% after reporting first-quarter revenues that missed the consensus on Wall Street.

• LSI Industries Inc. (Nasdaq:LYTS), down 8%, after reporting first-quarter earnings declined 70% from the year ago period and missed analysts’ estimates.