Chessie System Inc., citing record levels of coal shipments, yesterday reported that third-quarter profits jumped from $23.6 million ($1.19 a share) last year to $28.9 million $1.44).

For the nine-month period ended Sept. 30, the railroad reported record profits of $88.6 million ($4.41), up from $71.1 million ($3.58) for the same period in 1979.

Chessie also reported third-quarter revenues of $484 million, up from $460 million for the same quarter in 1979. For the first nine months of 1980, the company reported revenues of $1.5 billion, up from $1.4 million for the first three quarters of 1979.

In other reports, Hotel Investors Corp. said profits for the investment firm's fiscal year ended Aug. 30 jumped by 50 percent, rising to $4.95 million ($2.84 a share), up from profits of $3.3 million ($2.05) for the previous fiscal year. Fourth-quarter profits rose to $1.27 million (70 cents), an increase over 1979 fourth-quarter profits of $860,928 (51 cents).

The Chevy Chase investment company had gross sales for the fiscal year of $11.64 million compared with fiscal 1979 sales of $10.38 million.

American Realty Trust has reported a profits drop for the third quarter. Profits for the Arlington company's third quarter fell to $196,061 (9 cents a share) for the third quarter this year, down from $229,533 (10 cents) in 1979.

For the first nine months of the year, American Realty reported a loss of $171,287 (8 cents) compared with a loss of $1.31 million (59 cents).

Sales for the company's third quarter were $1.795 million, a slight increase over 1979 third quarter sales of $1.783. For the first nine months of 1980, the company reported sales of $4.52 million compared with sales of $4.51 million for the same period last year.