<PAGE>
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM 12b-25
NOTIFICATION OF LATE FILING
(CHECK ONE): / /Form 10-K / /Form 20-F / /Form 11-K /X/Form 10-Q / /Form N-SAR
For Period Ended: September 30, 1996
--------------------------------------------
/ / Transition Report on Form 10-K
/ / Transition Report on Form 20-F
/ / Transition Report on Form 11-K
/ / Transition Report on Form 10-Q
/ / Transition Report on Form N-SAR
For the Transition Period Ended:
------------------------------
- -------------------------------------------------------------------------------
NOTHING IN THIS FORM SHALL BE CONSTRUED TO IMPLY THAT THE COMMISSION HAS
VERIFIED ANY INFORMATION CONTAINED HEREIN.
- -------------------------------------------------------------------------------
If the notification relates to a portion of the filing checked above, identify
the Item(s) to which the notification relates:
- -------------------------------------------------------------------------------
PART I -- REGISTRANT INFORMATION
- -------------------------------------------------------------------------------
Full Name of Registrant ADVANCED RADIO TELECOM CORP.
- -------------------------------------------------------------------------------
Former Name if Applicable N/A
- -------------------------------------------------------------------------------
Address of Principal Executive Office (Street and Number)
500 108th Avenue N.E., Suite 2600, Bellevue, Washington 98004
- -------------------------------------------------------------------------------
City, State and Zip Code
PART II -- RULES 12b-25(b) AND (c)
If the subject report could not be filed without unreasonable effort or
expense and the registrant seeks relief pursuant to Rule 12b-25(b), the
following should be completed. (Check box if appropriate)
/X/ (a) The reasons described in reasonable detail in Part III of this
form could not be eliminated without unreasonable effort or
expense;
/ / (b) The subject annual report, semi-annual report, transition report
on Form 10-K, Form 20-F, 11-K or Form N-SAR, or portion thereof,
will be filed on or before the fifteenth calendar day following
the prescribed due date;
/ / (c) The accountant's statement or other exhibit required by Rule
12b-25(c) has been attached if applicable.
<PAGE>
PART III -- NARRATIVE
State below in reasonable detail the reasons why Forms 10-K, 20-F, 11-K, 10-Q,
N-SAR, or the transition report or portion thereof, could not be filed within
the prescribed time period.
THE REGISTRANT HAS NOT YET OBTAINED ALL INFORMATION REQUIRED TO COMPLETE
DISCLOSURES IN THE MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL
CONDITION AND RESULTS OF OPERATIONS AND IN THE NOTES IN THE FINANCIAL
STATEMENTS.
PART IV -- OTHER INFORMATION
(1) Name and telephone number of person to contact in regard to this
notification
David Chandler (206) 688-8700
---------------------------------- ----------------- ----------------------
(Name) (Area Code) (Telephone Number)
(2) Have all other periodic reports required under Section 13 or 15(d) of the
Securities Exchange Act of 1934 or Section 30 of the Investment Company
Act of 1940 during the preceding 12 months or for such shorter period
that the registrant was required to file such report(s) been filed? If
answer is no, identify report(s). /X/ Yes / / No
---------------------------------------------------------------------------
(3) Is it anticipated that any significant change in results of operations
from the corresponding period for the last fiscal year will be reflected
by the earnings statements to be included in the subject report or
portion thereof? / / Yes /X/ No
If so, attach an explanation of the anticipated change, both narratively
and quantitatively, and, if appropriate, state the reasons why a reasonable
estimate of the results cannot be made.
- -------------------------------------------------------------------------------
---------------------------------------------------
(Name of Registrant as Specified in Charter)
has caused this notification to be signed on its behalf by the undersigned
hereunto duly authorized.
Date 12/21/96 By /S/ THOMAS A. GRINA
--------------------------------------- ----------------------------
THOMAS A. GRINA,
EXECUTIVE VICE PRESIDENT
AND CHIEF FINANCIAL
OFFICER
