Lamar Advertising Co., a Baton Rouge-based outdoor advertising giant, reported its fourth-quarter profit rocketed to $207.9 million, or $2.18 per share, roughly 20 times the $10.1 million, or 11 cents per share, reported a year ago.

The results were boosted by a $120.1 million, one-time gain related to the company’s conversion to a real estate investment trust. The move allowed Lamar to write off a big chunk of its deferred tax liabilities. The trusts don’t pay corporate income taxes on profits if at least 90 percent of profits go to shareholders.

For the year, Lamar recorded earnings of $253.2 million, or $2.66 per share, compared with $39.8 million, or 42 cents per share, the prior year.

Lamar’s fourth-quarter highlights included a 4.4 percent increase in billing for same-unit digital signs and a 4 percent increase in revenue from analog posters, the smaller signs that are about 10 feet high and 22 feet wide.

Real estate investment trusts use different metrics to measure performance.

Lamar reported adjusted funds from operations for the fourth quarter of $117.3 million, or $1.23 per share, compared with $99 million, or $1.04 per share, a year ago. AFFO is a measure that helps predict a trust’s ability to pay dividends.

For the year, Lamar reported adjusted funds from operations of $388.5 million, or $4.08 per share, compared with $346.2 million, or $3.65 per share.

The company expects AFFO for 2015 of $417 million to $427 million, or $4.34 to $4.45 per share. Lamar projects 2015 net income of between $243 million and $253 million, or $2.53 to $2.64 per share.

Lamar’s stock dipped 46 cents, or 0.8 percent, to $57.90 Wednesday.