The value of Rand Capital Corp.’s investments grew by 7 percent during the fourth quarter, as growth in its stake in a West Seneca aircraft riveting equipment maker offset a continued decline in the value of its holdings in Buffalo Internet content provider Synacor Inc.

Rand increased the value of its 31 percent stake in Gemcor, a West Seneca company that makes automatic riveting machines for aircraft assembly, by $2.2 million, while the venture capital firm also upped its valuation of Amherst fingerprint reader manufacturer Ultra-Scan by more than $1 million.

In both cases, Gemcor and Ultra-Scan’s businesses have been strengthening, and the companies are finding greater acceptance of their products in the market, said Pete Grum, Rand’s president.

Those increases helped offset a nearly $3 million reduction in the value of the stock Rand owns in Synacor, whose shares have plunged since last summer as restrictions on selling by executives and other insiders have been listed and the company warned that its sales growth would slow this year.

Rand said it was carrying its shrinking stake in Synacor at its market value of $5.20 per share at the end of December, but the shares have slipped, closing at $3.28 Friday, down 1 cent.

Rand said it sold a little more than a quarter of its stake in Synacor during the fourth quarter, selling 227,200 shares at an average price of $5.57 per share, nearly four times its average cost of $1.42 per share.

Rand said all of its investments were valued at $25.8 million, or $3.90 per share, at the end of the year, up from $25.9 million, or $3.84 per share, at the end of September.

The venture firm said it repurchased 147,756 of its own shares during the quarter.

Rand’s stock currently trades at a 33 percent discount to its net asset value. Shares rose 10 cents Friday to $2.70.