Stamps.com, an El Segundo company providing Internet-based mailing and shipping services, was one of the week’s leading gainers on the Los Angeles Business Journal’s Stock Index of local companies, with shares up 21 percent to close at $116.51.

Second Sight Medical Products Inc., a Sylmar firm which develops and manufactures visual prosthetics, also had a good week. Shares rose 22 percent to close at $5.32 a share.

Cadiz Inc., a land and water resource development company in downtown Los Angeles, was one of the week’s biggest losers. Shares fell 20 percent to close the week at $4.70.